Contents
Page
Preface
3
Programme Introduction and Programme Design
4
Teaching Strategies
5
Contents of the Resource Package
6
Student Selection, Behavioral Characteristic of Students with
High Potential in Sciences
7
Lesson 1 : Nature of Science
8
Lesson 2 : Causal Inference-Mill’s Method in Causal Reasoning
27
Lesson 3 : Testing a Hypothesis
59
Lesson 4 : Experimental Designs
82
Lesson 5 : Double-blind Design in Randomised Experimental
Design
108
Lesson 6 : Critical Thinking in Engineering Process
130
Lesson 7 : Arguments in Science
146
Lesson 8 : Analogies in Science
158
Lesson 9 : Pseudoscience
184
Programme Evaluation
202
Student Questionnaire
203
Statistics of Student Questionnaire
204
Extract from Students’ Questionnaires
205
Links of the Interview Videos
206
Behavioral Checklist of Student with High Potential in Sciences
207
References & Recommended Book List
211
Preface
It has been my great honour to serve as a consultant for the programme “Enhancing Thinking
Skills in Science Context” and I applaud the achievement of the programme team in developing
this resource package for teaching gifted students the methods of science.
In the case of language learning, it is common that one could be a native speaker of a language
without direct knowledge of many of its grammatical rules. Similarly, in science education, one
could also learn how to practice science without receiving direct instruction on the underlying
methods used in various scientific activities. Although many skills, including scientific reasoning,
could be learned in a case-by-case (bottom-up) manner by following typical examples, this teaching
method has many limitations, including the difficulty to transfer skills that are learned in one
domain to another. In science education, these limitations could be overcome by the supplement
of the top-down approach in which the underlying rules and principles of scientific reasoning are
identified and made explicit to students in the learning process. This approach is followed in this
resource package.
Students may find the top-down approach difficult to follow because abstraction and generalization
are required in understanding the rules and principles of scientific reasoning. This resource package
has made very good use of well-chosen historical and daily life examples to illustrate various
methods of science. It greatly reduces the level of difficulty in learning the subject, and so I believe
that the package is a very useful and effective toolkit for teaching scientific methods.
Besides focusing on the application of various scientific methods, the package also puts great
emphasis on developing students’ awareness of their limitations. This can enhance their ability to
think critically in scientific investigation. This ability is essential for the advancement of science
because many great scientific discoveries and invention were results of critical but not mechanical
applications of scientific methods. This package has therefore adopted a very sound approach that
can enhance students’ ability to push the frontier of scientific knowledge forward.
Dr Chan Ho Mun
Associate Professor of Philosophy
Department of Public and Social Administration
City University of Hong Kong
( This resource package can be downloaded from http://resources.edb.
gov.hk/gifted/Learning_&_Teaching_ResourcesII/ )
P2
P3
Programme Introduction
Teaching Strategies
The theme of this science pull-out programme is “Enhancing Thinking Skills in Science Context”.
It aims to enhance students’ thinking skills through the learning of some science related topics. The
designed activities provide junior secondary students opportunities to develop their critical thinking,
problem-solving as well as decision making skills, which are deemed to be very important elements
of an enrichment programme for the gifted students. Students are familiar with some of the topic
contents related to scientific investigation. Unfamiliar topics such as analogy and pseudoscience
are also included in the programme to provide challenges to the students. Furthermore, the learning
content of such topics relates real life examples to the study, which may motivate the students to
learn better.
According to Gallagher(1985) the learning content, learning process and the learning environment
of the basic curriculum need to be modified to match the characteristics and the needs of the gifted.
Another expert in gifted education, VanTassel-Baska (1988) advocated that a gifted curriculum
should attend to the content mastery and the learning process. Hence, gifted students should be
taught with advanced content, higher order thinking and problem-solving skills. The teacher should
act as a facilitator to motivate students to learn actively. The teacher may use effective questioning
technique to promote thinking in science context. Open questions are useful in stimulating higher
level thinking. Students need to be encouraged to justify their ideas, evaluate the reasoning of
a claim and a conclusion. The teacher may use real life example to enhance problem-solving
and decision making skills of students. Furthermore, the teacher should allow the students to
have choice in doing the class work or assignment and note the learning styles of different gifted
students. Finally but not the least, the teacher should maintain a warm classroom atmosphere so
as to encourage more teacher-student as well as student-student interaction which is benefical to
deep learning.
Programme Design
Many academics such as Joyce VanTassel-Baska advocated that key components of a science
curriculum for the gifted students should
1. develop an understanding of scientific concepts;
2. develop scientific inquiry skills in collaborative settings;
3. let them learn significant content in science areas;
4. develop interdisciplinary connections;
5. develop investigations of real problems and
6. develop scientific habits of mind.
In addition to the conceptual learning outcomes, thinking skills should also be introduced to gifted
students. In this connection the programme “Enhancing Thinking Skills in Science Context” is thus
designed to include many activities to provide chance for the students to enhance their problem
solving, critical thinking and decision making skills. Students are required to test their hypotheses,
analyze the data, evaluate the evidence and then draw conclusions. They also learn advanced
science concepts and are required to solve interdisciplinary problems in science and statistics
(double-blind design).
P4
P5
Contents of the Resource Package
Author
Gifted Education Section, Curriculum Development Institute, Education
Bureau
Target Students
S1-S2
Teaching mode
Pull-out enrichment programme
KLA
Science
Lessons
9 lessons (90 minutes each except Lesson 5 (180 min.))
Lesson 1: Nature of Science
Lesson 2: Causal Inference-Mill’s Method in Causal Reasoning
Lesson 3: Testing a Hypothesis
Lesson 4: Experimental Designs
Lesson 5: Double-blind Design in Randomised Experimental Design
Lesson 6: Critical Thinking in Engineering Process
Lesson 7: Arguments in Science
Lesson 8: Analogies in Science
Lesson 9: Pseudoscience
Acknowledgments Pilot schools (2006-07)
St. Paul’s Co-educational College (English version)
Ms. Lau Oi Ha & Ms. Wong Pui Lan
HKMLC Queen Maud Secondary School (Chinese version)
Ms. Lo Sin Kei & Mr. Wong Ting Ho
Mr. Kevin K.L. So (Engineer)
(Contributing professional advice on Lesson 6)
Fukien Secondary School (Chinese version)
Mr. Chau Kwok Leung
Dr. Chan Ho Mun (Programme Consultant)(Associate Professor of
Philosophy, Department of Public and Social Administration, City
Unversity of Hong Kong)
P6
Student Selection
Teachers are advised to use multiple methods channels such as classroom observation, behavioral
checklist, parent/peer group/self recommendation, students’ products and assignments, awards in
local and/or international science competitions to select students with high potential in science
to take part in the school-based enrichment programme. A single test/indentification tool is not
reliable in the indentfication of a scientifically gifted student.
Behavioral Characteristics of Students with
High Potential in Sciences
(a) Persistent in learning science, high concentration, hard working and motivated;
(b) Interested in science books and science related television programmes;
(c) Enjoys solving problems in sciences;
(d) Organises data or analyses an observed phenomenon to discover patterns or relationships;
(e) Good at observing, exploring, questioning, investigating things in detail;
(f) Understands scientific methods, able to formulate hypotheses and conduct experiments
carefully;
(g) Skillful in using laboratory equipments, able to improve on experiments;
(h) Demonstrates creativity in invention and/or experimental designs;
(i) Demonstrates task commitment in science projects(sticking with investigations in spite of
difficulties or problems).
P7
Suggested Learning and Teaching Activities
Lesson 1 Nature of Science
Level of Students: S.1-S.2
Suggested Lesson Time: 90 min.
Learning Objectives:
Students will:
 gain an understanding of the Nature of Science;
 be able to use induction in science reasoning.
Materials for each group:
Activity 1
 Coloured tokens (red, yellow, blue, green, white)
 Opaque plastic bags for holding the tokens
Activity 2
 Red packets
 Ten-dollar bank notes
Prior knowledge of students:
Students should learn the basic scientific investigation method in S.1. The teacher
can ask a few simple questions about scientific investigation and the nature of science
to have a general idea of students’ knowledge on these topics.
Suggested Learning and
Teaching Activities:
Lesson 1 Activity 1 (A game to model
the nature of science)
Time allocation
Activity 2 (Red Packets
Activity)
15 min
90 min.
35 min.
Remarks
The focus of Activity 1 is to
let students experience what
scientists do in scientific
research and hence broaden
students’ knowledge on
the nature of science. The
activity models the scientific
process, including putting
forward a hypothesis, carrying
out experiments and getting
results to see whether the data
supports or does not support
the hypothesis.
The focus of Activity 2
is to motivate students to
think about prediction based
on induction (statistical
induction);
The teacher may ask students
to comment on the use of this
method in science.
Activity 3, 4 and 5
40 min
Activity 3 shows the students
the structure of a logical
argument (premise(s) and
conclusion).
Activity 4 & 5 are exercises
on using induction in science
reasoning.
P8
P9
PowerPoint
What is science?
L e s s on 1

Nature of Science
Activity 1:
Material: coloured tokens, opaque plastic bags
What do you know about scientific method?
What are the steps involved in scientific
investigation?
Materials:
Red packets & Ten-dollar bank notes
Instruction:
 You are given some red packets.
 Each of you will take turns to open a red
packet and then you are required to tell
your classmates what is inside the red
packet.
Activity 1:
Activity 2:

Instruction:
 The class is divided into groups of 5 students. In each group 3 students
would act as the team players while 2 students will act as observers,
observer A and B.

All the observer As and Bs will go outside the classroom when the teacher
explains to the team players the rules of the game. Then all the observers
will come back to the classroom and observe the team players to play the
game.

After 1 minute, the observers will be allowed to play the game. If the
observers play wrongly, team players can only say the word “wrong” but
they are not allowed to give further hints.


Activity 1:


The observers need to record their
observations and hypotheses about the
rules of the game.
The time limit for the game with the
participation of the observers is 2 minutes.
Then the observers are required to present
the rules of the game.
Activity 1:
What are your hypotheses?
Do your data support your hypotheses?


P 10
The focus on doing Activity 1 is to let you
experience what scientists do in scientific research
and hence broaden your knowledge on the nature
of science.
The activity models the scientific process, including
putting forward a hypothesis, carrying out
experiments and getting results to see whether the
data supports or does not support the hypothesis.
Activity 2:
Activity 2:



Do any of your red packets contain
money?
Predict the possibility that next red
packet would contain money and explain
your prediction.
Induction
The focus of Activity 2 is to stimulate you
to think about prediction based on
induction (statistical induction);
Comment on the use of induction in
science.


Induction is the process of reasoning
from particular facts or ideas to a general
rule or law.
In induction, scientists use separate
observations to arrive at general
principles.
Activity 3
Activity 3
Q3.1. What is the colour of swans?
__________________________________


Q3.2. Do you have any comments on the
following arguments?
__________________________________

P 11
All the swans in France are observed as
white.
All the swans in Germany are also
observed as white.
Then, all swans in the world are white in
colour.
Activity 3
Activity 3


Suggested Solution
A
=B
C
=B
X (including A & C) =B
In fact, the above statements are examples
of logical statements.
Try to present the above statements in
Mathematical terms.
Activity 4





Activity 3


Activity 3
The Structure of a Logical Argument involves a
premise/premises and a conclusion.
Arguments all follow a certain basic structure. They begin
with one or more premises. Premises are facts and
these facts are used as the starting point of an argument.
Then a principle of logic is applied in order to come to a
conclusion.


Please write logical statements about the colour of swans:





Activity 4


Activity 4
Dropping from a certain height above the ground, a ping pong ball
bounces back to smaller heights and then finally stops bouncing.
Dropping from a certain height above the ground a basket ball
bounces back to smaller heights and then finally stops bouncing.
Dropping from a certain height above the ground a football bounced
back to smaller heights and then finally stops bouncing.
Dropping from a certain height above the ground a tennis ball
bounces back to smaller heights and then finally stops bouncing.
Dropping from a certain height above the ground, all balls with
properties of balls bounce back to smaller heights and then finally
stop bouncing.
All the swans in France are observed as
white.
All the swans in Germany are also
observed as white.
Then, all swans in the world are white in
colour.
Activity 5 (True or False)
Remarks: The conclusion drawn by the
method of “Induction by examples” may
or may not be true. Once there is an
exception, the conclusion can be
overthrown.






Using the example of the white swans
Premise1:
A (In France all the swans are observed
as white)
=B
(All the swans are observed as white.)
Premise2:
C (In Germany all the swans are
observed as white)
=B
(All the swans are observed as white)
Activity 4
Logical connection-Hence
Conclusion:
X (including A & C) = B
In the world (including France and Germany) all the swans are observed as
white = All the swans are observed as white

When a ping-pong ball, a basket ball, a
football, a tennis ball are dropped from a
certain height above the ground, they
would fall on the ground, bounce back
and finally stay on the ground.
Try to write down some logical
statements about the above phenomena.




P 12

Activity 5

Your conclusion is based on some observations and experiments.
Q4.1. Are the results of your experiments consistent without
contradiction?
______________________________________________________
Q4.2. Suppose you are given a ball made of a certain material, X
and required to carry out the same experiment as above, how would
you comment on your previous conclusion if you got a contradictory
result later?
______________________________________________________
______________________


All living things are composed of basic units
called cells. ( )
All black parents will give birth to black
babies.(
)
All jelly fish (more than 10,000 species in the
sea) are toxic to humans.( )
All matters are made of particles called atoms.
( )
All headaches can be relieved by taking
panadol. ( )






P 13
All swans are white. ( )
All plants possess chlorophyll. ( )
All fishes breathe with gills. ( )
All newborn mammals feed on mothers’
milk.( )
All snakes reproduce by laying eggs.( )
All swans are white. (F)
All plants possess chlorophyll. (F)
All fishes breathe with gills. (F)
All newborn mammals feed on mothers’ milk. (T)
All snakes reproduce by laying eggs. (F)
All living things are composed of basic units called
cells. (T)
All black parents will give birth to black babies. (F)
All jelly fish (more than 10,000 species in the sea) are
toxic to humans. (F)
All matters are made of particles called atoms. (T)
All headaches can be relieved by taking panadol. (F)
Teachers’ Reference
Q5.1. Can you think of some other ways to
enhance the validity of the conclusion
drawn by the method “induction by
examples”?
___________________________________





Suggested Solution:
increase the number of targets during
observations
increase the range of targets
a positive attitude towards contradictory
examples
Lesson 1 Nature of Science
Learning Objectives
Students will
 gain an understanding of the nature of science and scientific method;
 be able to use induction in science reasoning.
Activity 1: A game to model the nature of science
Material: coloured tokens

Q5.2. What is the value of drawing conclusion
by induction by examples?
__________________________________
__________________________________



Suggested Solution:
It is impossible to investigate all cases or
examples to establish a scientific relationship /
theory / principle.
One of the advantages of using the method of
induction by examples is that it is more
practicable as long as the sampling method is
appropriate.
The law of conservation of energy in Physics is
established by using the method of induction by
examples.
The class is divided into groups of 5 students. In each group, 3 students act as the team players
while 2 students act as observers, observer A and B. All the observer As and Bs go outside the
classroom when the teacher is explaining to the team players the rules of the game. Then all the
observers come back to the classroom and observe the team players to play the game. After 1
minute the observers will be allowed to play the game. If the observers play wrongly, team players
can only say the word “wrong” but they are not allowed to give further hints. The observers need
to record down their observations and hypotheses. The time limit for the game with the observers
is 2 minutes. Then the observers are required to present the rules of the game. The teacher may
consider requesting observer As and Bs to do two different tasks, task 1 and task 2.
Task 1: Guess the rules of the game (a more open guess).
Task 2: Guess the rules of the game (Hints: guess the value sequence of the tokens, i.e. which
token is most expensive, which one is the second expensive, etc.)
Task 1 and 2 may be written in a word card. Observer As and Bs may not know the task of
others.
Rules of the game:
 Red, yellow, blue, green and white tokens are put inside an opaque plastic bag.
 Players take turns to pick out one token each time at random (without seeing the tokens from
the bag) and then put the token on the table.
 When a more expensive token is newly picked out of the bag and put on the table, team
players need to touch the pile of tokens.
 When a less expensive token is picked out of the bag, there is no need to touch the pile of
tokens.
 When a token taken out of the bag has the same value as the preceding one, there is no need to
touch the pile of tokens.
P 14
P 15
Remarks:
Activity 3:
Observer As and Bs experience what scientists do in scientific research. First, they observe how the
team players play the game and have their own hypothesis. They then play with the team players
according to their own hypothesis (i.e. carry out experiments) and get feedback from the team
players (get result). If they can play the game according to the rule, they are allowed to play the
game continuously. Hence, the hypothesis is supported.
Q3.1. What is the colour of swans?
_____________________________________________________________________________
Activity 2:
Students are given some red packets (only one red packet contains a 10-dollar bank note). Each
of them needs to open the red packets one by one and tell their classmates what is inside the red
packet.
Ask students to predict the possibility that next red packet would contain lucky money after one
student opens the red packet with a 10-dollar bank note.
Q3.2. Do you have any comments on the following argument?
All the swans in France are observed as white.
All the swans in Germany are also observed as white.
All the swans in Rome are also observed as white.
Then, all swans in the world are white in colour.
_____________________________________________________________________________
_____________________________________________________________________________
In fact, the above statements are examples of logical statements.
_____________________________________________________________________________
Try to present the above statements in Mathematical terms.
Suggested Solution
A=B
C=B
X (including A & C) = B
_____________________________________________________________________________
The Structure of a Logical Argument involves a premise/premises and a conclusion.
Remarks:
Some students may say the chance is 50/50. Some may say it is most probably that the next red
packet is empty. Others may say no one knows. The purpose of this activity is to motivate students
to think about the use of generalisation in drawing a conclusion. The teacher may then discuss
with the students the use of induction in science. The term statistical induction (activity 2) may
also be mentioned.
Arguments all follow a certain basic structure. They begin with one or more premises. Premises
are facts and these facts are used as the starting point of an argument. Then a principle of logic is
applied in order to come to a conclusion.
What are your comments on predicting whether or not the next red packet would contain money?
Induction is a process of reasoning from particular facts or ideas to a general rule or law. In induction
scientists use separate observations to arrive at general principles.
Please write down the logical statements about the colour of swans.
Using the example of the white swans
Premise1:
A (In France all the swans are observed as white)=B (All the swans are observed as white.)
Premise2:
C (In Germany all the swans are observed as white)=B (All the swans are observed as white)
Logical connection-Hence
Conclusion: X (including A & C) = B
In the world (including France and Germany) all the swans are observed as white = All the swans
are observed as white
P 16
P 17
Activity 4
When a ping-pong ball, a basket ball, a football, a tennis ball are dropped from a certain height
above the ground, they fall on the ground, bounce back and finally stay on the ground. Try to write
down some logical statements about the above phenomena.
Dropping from a certain height above the ground, a ping pong ball bounces back to smaller heights
and then finally stops bouncing.
Dropping from a certain height above the ground, a basket ball bounces back to smaller heights
and then finally stops bouncing.
Dropping from a certain height above the ground, a football bounces back to smaller heights and
then finally stops bouncing.
Dropping from a certain height above the ground, a tennis ball bounces back to smaller heights and
then finally stops bouncing.
Dropping from a certain height above the ground, all balls with properties of balls bounce back to
smaller heights and then finally stop bouncing.
Your conclusion (logical statements) is based on some observations and experiments.
Q4.1. Are the results of your experiments consistent without contradiction if you carry out the
above experiments?
______________________________________________________________________________
Q4.2. Suppose that you are given a ball made of a certain material, X and required to carry out
the same experiment as above, how would you comment on your previous conclusion if you get
contradictory results later?
______________________________________________________________________________
Q5.1. Can you think of ways to enhance the validity of the conclusion drawn by the method
“induction by examples”?
______________________________________________________________________________
Suggested Solution:
a. Increase the number of targets during observation
b. Increase the range of targets
c. A positive attitude towards contradictory examples
Q5.2. What is the value of drawing conclusion by induction by examples?
Suggested Solution:
It is impossible to investigate all cases or examples to establish a scientific relationship / theory /
principle. One of the advantages of using the method of induction by examples is that it is more
practicable as long as the sampling method is appropriate. The law of conservation of energy in
Physics is established by using the method of induction by examples.
Remarks: The conclusion drawn by the method of “induction by examples” may or may not be
true. Once there is an exception, the conclusion can be overthrown.
Activity 5 (True or False)
Please put the correct answer (T=true; F=false) in the following brackets:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
All swans are white.
All plants possess chlorophyll.
All fishes breathe with gills.
All newborn mammals feed on mothers’ milk.
All snakes reproduce by laying eggs.
All living things are composed of basic units called cells. All black parents will give birth to black babies.
All jelly fish (more than 10,000 species in the sea) are toxic to humans.
All matters are made of particles called atoms. All headaches can be relieved by taking panadol. P 18
( F
( F
( F
( T
( F
( T
( F
( F
( T
( F
)
)
)
)
)
)
)
)
)
)
P 19
Further Reference on Activity 5
Item 1. All swans are white
A Dutch explorer, Willem de Vlamingh, first reported to the world that he saw a black swan in
Australia in 1697. Since then, throughout the world, seven species of swans have been identified.
There are only two that are not pure white, the South American Black-necked Swan and the
Australian Black Swan. Nowadays, Black Swans are common and numerous in Australia.
Reference on Scientific Method
The set of procedures by which scientists study the world is known as the scientific method.
Scientific Method usually consists of:
Observation
Item 3. All fishes breathe with gills.
Lung fish is an obligate air breather, possessing a swim bladder with alveolar tissue that serves as
a rudimentary lung.
Scientists use their senses (scientists concern with what they see, hear, feel, taste and smell) to
study the world. They usually use tools (instruments) to extend their senses.
Testing ideas
Item 5. Most snakes are oviparous (laying shelled eggs); some are ovoviviparous (giving
birth to well-formed young); very few are viviparous (giving birth to young with a primitive
placenta for exchange of materials between embryonic and maternal bloodstreams).
Item 7. All black parents will give birth to black babies.
It was reported that a couple who were biracial themselves gave birth to two twin sisters. The
couple’s mothers are both white and their fathers are black. One of the twin sisters was blonde and
fair skinned while the other was black. Two eggs were fertilised at the same time in the mother’s
womb and the mother gave birth to the two twin sisters.
Scientists would test their ideas so as to construct a hypothesis to explain the observation. They
may carry out experiments to test their hypotheses. When they do experiments, they would change
the factor to be studied and keep other variables constant (fair test).
Hypothesis
Scientists may use induction or deduction to test their hypotheses. In induction scientists use
separate observations to arrive at general principles. In deduction scientists arrive at a specific
conclusion from general principles.
Skin colour is determined by different genes working together. If a woman is of mixed race, her
eggs usually contain a mixture of genes coding for both black and white skin. Similarly, a man of
mixed race has a variety of genes in his sperm. When these eggs and sperm fuse together, they will
create a baby of mixed race. If both the egg and sperm contain all white genes, the baby will be
white. And if both contain just the versions necessary for black skin, the baby will be black.
Item 8. All jelly fish are toxic to humans.
There are more than 10,000 species of jellyfish in the sea. More than 100 species of the jellyfish
are toxic to humans causing cutaneous rashes or cardiovascular/ respiratory collapse. (http://sky.
prohosting.com/minogue2/sting/jellyfishsting-836.htm retrieved on 9 Nov. 06)
Item 10. All headaches can be relieved by taking panadol.
This is not true because there is individual difference regarding the response to a drug.
P 20
P 21
Testing Hypothesis (II)
Testing Hypothesis (I)
Specific observations
Specific observations
It is observed that
z
copper, aluminium, gold and iron are metals;
z
all of them are at solid state under room temperature and
pressure.
It is observed that
z
copper, aluminium, gold and iron are metals;
z
all of them are at solid state under room temperature and
pressure.
Induction
Induction
General hypothesis
General hypothesis
All metals are at solid state under room temperature and pressure.
All metals are at solid state under room temperature and pressure.
Deduction
Therefore general
hypothesis is
rejected.
Specific Hypothesis
General
Hypothesis
is accepted.
Deduction
Specific Hypothesis
It is believed that all metals are at solid state under room temperature and pressure.
˜̇ʳ˼̆ʳ˵˸˿˼˸̉˸˷ʳ̇˻˴̇ʳ˴˿˿ʳ̀˸̇˴˿̆ʳ˴̅˸ʳ˴̇ʳsolid state under room temperature and
pressure.
Metal X has metallic properties Î Metal X should be at solid state under room
temperature and pressure.
Metal X has metallic properties Î Metal X should be at solid state under
room temperature and pressure.
Testing (e.g. controlled experiments)
Specific
Hypothesis
is accepted.
Specific
Hypothesis
is false
Specific observations
If metal X is at solid state under room temperature and
pressure,
Testing (e.g. controlled experiments)
Specific observations
If metal X is NOT at solid state under room temperature and
pressure,
Reference: Peter Castro & Michael E. Huber (2005)
P 22
P 23
Students’ Worksheet
The Structure of a Logical Argument involves a premise/premises and a conclusion.
Arguments all follow a certain basic structure. They begin with one or more premises. Premises
are facts and these facts are used as the starting point of an argument. Then a principle of logic is
applied in order to come to a conclusion.
Please write down the logical statements about the colour of swans:
Lesson 1 Nature of Science
Activity 1:
Material: coloured tokens, opaque plastic bags
Instruction:
(a). The class is divided into groups of 5 students. In each group 3 students act as the team
players while 2 students act as observers, observer A and B.
(b). All the observer As and Bs will go outside the classroom when the teacher explains to the
team players the rules of the game. Then all the observers will come back to the classroom
and observe the team players to play the game.
(c). After 1 minute the observers will be allowed to play the game. If the observers play
wrongly, team players can only say the word “wrong” but they are not allowed to give
further hints.
(d). The observers need to record down their observations and hypotheses about the rule of the
game.
(e). The time limit for the game with the participation of the observers is 2 minutes.
(f). Then the observers are required to present the rules of the game.
Activity 2:
You are given some red packets. Each of you needs to open the red packets one by one and tell
your classmates what is inside the red packet.
Activity 4
When a ping-pong ball, a basket ball, a football, a tennis ball are dropped from a certain height
above the ground, they would fall on the ground and bounce back and finally stay on the ground.
Try to write down some logical statements about the above phenomena.
Your conclusion is based on some observation and experiments.
Q2.1.
Predict the possibility that the next red packet would contain lucky money and explain your
view points.
Q4.1.
Are the results of your experiments consistent without contradiction?
_____________________________________________________________________________
_____________________________________________________________________________
Activity 3
Q3.1.
What is the colour of swans?
Q4.2.
Supposing that you were given a ball made of a certain material, X and required to carry out the
same experiment as above, how would you comment on your previous conclusion if you get
contradictory result later?
_____________________________________________________________________________
_____________________________________________________________________________
Q3.2.
Do you have any comments on the following argument?
All the swans in France were observed as white.
All the swans in Germany were also observed as white.
Then, all swans in the world were white in colour.
_____________________________________________________________________________
In fact, the above statements are examples of logical statements.
Try to present the above statements in Mathematical terms.
P 24
P 25
Suggested Learning and Teaching Activities
Activity 5 (True or False)
1. All swans are white.
(
2. All plants possess chlorophyll.
(
3. All fishes breathe with gills.
(
4. All newborn mammals feed on mothers’ milk.
(
5. All snakes reproduce by laying eggs.
(
6. All living things are composed of basic units called cells. (
7. All black parents will give birth to black babies.
(
8. All jelly fish (more than 10,000 species in the sea) are toxic to humans.( 9. All matters are made of particles called atoms. (
10. All headaches can be relieved by taking panadol. (
)
)
)
)
)
)
)
)
)
)
Q5.1.
Can you think of ways to enhance the validity of the conclusion drawn by the method “induction
by examples”?
Lesson 2 Causal Inference-Mill’s Method in Causal Reasoning
Level of Students: S.1-S.2
Suggested Lesson Time: 90 min.
Learning Objectives:
Students will:
 gain an understanding of Mill’s Method in causal reasoning
 be able to use Mill’s Method to analyse and interpret observations for the purpose of drawing
conclusions about the causal relationships they exhibit
 be able to understand the limitations of Mill’s Method in causal reasoning
Materials and Apparatus for each group:
Michael Faraday’s Experiment
_____________________________________________________________________________
_____________________________________________________________________________
Q5.2.
What is the value of drawing conclusion by induction by examples?
copper coil
ammeter
A
_____________________________________________________________________________
_____________________________________________________________________________
1 ammeter, 1 copper coil, 1 bar magnet, 1 iron bar, connecting wires
Prior knowledge of students:
Students should have the basic knowledge of scientific investigation learnt in S.1. The teacher
can ask students a few simple questions on causal reasoning to understand how much they know
on the topic.
P 26
P 27
Suggested Learning and Teaching Time allocation
Activities:
Lesson 2
90 min.
Causal Inference-Mill’s Method
in causal reasoning
Activity 1a & 1b
(Method of Agreement)
Activity 2
(Method of Difference)
Activity 3
(Joint Method of Agreement and
Difference)
20 min
20 min
Remarks
The students are divided into groups
of 4-5 members. The team-mates are
required to discuss the cases together
and prepare a presentation. The teacher
then discusses the findings with the
students and comments on the use of
Mill’s Method in causal reasoning.
The focus of Activity 1a and 1b is to
let students know the logic of using
Method of Agreement (Mill’s method)
in causal reasoning and its limitation:
 People will be blinded by apparent
causal relationship but in fact there are
real reasons other than that of observed.
 Cannot observe all possible cases
The focus of the Michael Faraday’s
Experiment is to let students know the
logic of using Method of Difference
(Mill’s method) in causal reasoning and
its limitation:
 If there are more than one variable
in the experimental design, the results
obtained are not conclusive.
Teacher may ask the following question
to relate “fair test” to Method of
Difference:
“We usually use “fair test” in scientific
investigation. Does the “fair test”
idea match with Mill’s Method of
Difference?”
Suggested answer:
Mill’s Method may include two or
several experimental groups and one
control group. In this sense it is similar
to fair test experiments.
The focus of Activity 3 is to let students
know the logic of using Joint Method
of Agreement and Difference in causal
reasoning and its limitation:
 Should observe more cases to
minimise the chance factor, otherwise
cannot avoid co-incidence or unrelated
situations
20 min
P 28
Activity 4
(Method of Residues)
10 min.
The focus of Activity 4 is to let students know
the logic of using Method of Residues in
causal reasoning and its limitation:
 Sometimes it is difficult to use the Method
of Residue to find the causal relationship
because the remaining factor found is a
compound factor. As in the discovery
of radium, Marie Curie first isolated Po
(plutonium) and then found radium which
contributed to the major difference in the
observed radioactivity of the uranium sample.
Activity 5
(Method of Concomitant Variation)
20 min.
The focus of Activity 5 is to let students know
the logic of using Method of Concomitant
Variation in causal reasoning and its
limitation:
 Two events have correlation but it is not
necessary for them to have causal relationship.
For instance, many overweight people would
die at young ages. However, overweight is
not a direct cause of early death.
 Many irrelevant factors would increase or
decrease concomitantly. For instance, both the
average rain falls per year and the birth rates
in Hong Kong have been decreasing. It is
unlikely that the amount of rainfall affects the
birth rate.
 There is a limit to the degree of change in
circumstance and effect.
 The circumstance must be the only cause
for the effect.
P 29
PowerPoint
Enhancing Thinking Skills
in Science Context
Causes
Lesson 2
Causal Inference – Mill’s Methods of
causal reasoning
Effects
Inductive reasoning
Task 1a:
Task 1a:
1. Use flow charts / comparison tables /
diagrams to illustrate how Dr. R arrived at
his proposition that mosquitoes might be
responsible for the transmission of the
micro-organisms that cause disease X.
2. Use simple diagrams to show the logic of
the causal relationship in case 1(a).
Causal relationships among events
Activity 1a
Form 5 groups

Disease X was recorded long time ago. People
with disease X would have shaking chills at
regular time intervals (usually at mid-day
between 11 a.m. to 12 noon), followed by high
fever lasting for 2 to 6 hours. The patients may
also have symptoms like headaches, vomiting,
delirium, anxiety and restlessness.

It was also discovered that the blood of the
infected patients contained a micro-organism that
was a new species of parasite at that time.
Study and discuss the
given cases
Group presentation


In an uneventful afternoon, four students
of school A suffered from severe diarrhea.
All of them went to the hospital and the
doctor naturally suspected that the
symptom might be related to the food
eaten by the students during lunch.
Student
Activity 1a

Activity 1b
Activity 1b
Activity 1a
Some doctors# also observed that people
sleeping outdoors were more susceptible to
get the disease than those sleeping indoors;
A doctor (Dr. R) made a lot of efforts in the
research of disease X. He observed that
Disease X was widely spread in the following
areas in 1895:
people sleeping near a camp fire were less
susceptible to get the disease.
Activity 1a
Activity 1a
Place
Natural Environment
A
Near a river
B
Inside a forest
C
Near the marshes
D
Paddy fields

Dr. R also observed that there were
a lot of mosquitoes in places A, B, C
and D. He suggested that
mosquitoes might be responsible for
the transmission of the microorganisms that caused Disease X.
Food items
1
pizza, orange juice, cookie,
vegetable salad
2
hot dog, French fries, vegetable
salad, iced tea
3
pizza, vegetable salad, coca cola,
cheese cake
4
hamburger, orange juice,
vegetable salad, cheese cake
The doctor asked the students what
they ate for lunch and their answers
were as follows:
Task 1b:
Task 1b:
1.
Use a table / diagram to show the logic of
the possible cause of diarrhea among the
students.
2.
Do you know the name of this method of
establishing causal relationship?
3.
What is the precaution of applying the
method (in (2)) in causal reasoning?
Task 1b:
Case/event
Circumstance
Effect
1
B, C, D, A
x
2
E, F, A, G
x
3
B, A, H, I
x
4
J, C, A, I
x
Conclusion:
P 30

Mill’s Method of Agreement (求同法)
A is the cause of x
P 31
Task 1b:


Activity 2
You may get the answer “vegetable salad” from
the Method of Agreement. But the pathology tests
showed that there were no bacteria causing
diarrhea found in the vegetable salad. The actual
cause why these four students suffered from
diarrhea was that the forks they used to eat the
vegetable salad were contaminated with bacteria.
Micheal Faraday’s
Electro-magnetic
People will be blinded by apparent causal
relationship but in fact there are real reasons
other than that of observed. For instance, in the
malaria case above people believed that the cause
of malaria was marsh but the true reasons are
that the parasites that cause malaria can be
carried by mosquitoes that breed in water.
Answer:
Mill’s Method of Difference (求異法)
2.
Place a bar magnet into the copper coil (no
movement of the magnet) and observe the reading
of the ammeter.

Discovery of a ‘strange’ disease
by Dr. Sun Simiao (孫思邈)
1.
Activity 3
Design a table to record the results of the
above experiment.
2.
Suggest the cause of the change (if any) in
Faraday’s Experiment.
3.
Use a comparison table / diagram to show the
logic of the discovery by Faraday.
4.
Do you know the name of the method (in (3))
of establishing the causal relationship?
No
No
Movement of iron
What is the precaution of applying the method
(in (4)) in causal reasoning?
Yes
Movement of the
pointer of ammeter
No
No
No
Answer:

Movement of magnet
Yes
Movement of the
pointer of ammeter
Yes
He then noted that the disease was not found among
the poor people who ate coarse rice. He concluded that
the cause of the disease was related to the eating of
polished rice. He then asked the patients to eat coarse
rice instead of polished rice. Luckily, all the patients
were cured within half a month.
Task 2
Task 2
Task 3:
2. Suggest the cause of change (if any) in Faraday’s Experiment.
3. Use a comparison table / diagram to show the
logic of the discovery by Faraday.
1.

Case/event
1
2
All the famous doctors could not treat the diseases.
Dr. Sun was invited to treat one of the patients. He went to the
kitchen of one of the rich patients. The cook told him that his
master did not like to eat too much meat and fish but he liked to
eat polished rice (white rice which had been polished several times).
Dr. Sun also paid visits to several rich patients who suffered from
the same diseases. He found that these patients had the same
habit of eating polished rice.
2.
Do you know the name of the method
(in (1)) of establishing the causal
relationship?
3.
What is the precaution of applying the
method (in (2)) in causal reasoning?
Task 3:
Use a table / diagram to show the logic of the
discovery of the cause of the disease.
2. Do you know the name of the method (in (1)) of
establishing the causal relationship?
Circumstance
A, B, C
- B, C
Effect
x
x
Case
Conditions
Answer:
Symptom
W
X
Y (ate
polished rice)
leg edema, muscle pain,
fatigue and tiredness
Patient A
(rich) (+ve gp)
Yes
No
Yes
Yes
Patient B
(rich) (+ve gp)
No
No
Yes
Yes
C
(poor) (-ve gp)
Yes
No
No
No
D
(poor) (-ve gp)
No
Yes
No
No
Mill’s Joint Method of Agreement and Difference
(求同求異並用法)
Conclusion: A is the cause of x
P 32

Answer:
Answer:
Conclusion: change of magnetic field
causes generation of electricity.
Their symptoms included leg edema, muscle pain, fatigue and
tiredness.
Task 3:
1.
Use a table / diagram to show the logic
of the discovery of the cause of the
disease.
Design a table to record the results of the above experiment.
1.
It’s the movement of the magnet that
causes the pointer of the ammeter moves.
All of them got a strange disease at the same time.


Task 2
Dr Sun Simiao (孫思邈) (AD 581-682) was a very famous doctor in
Tang Dynasty. There were several rich people living in the capital
of China, Changon.

Repeat steps (3) and (4) by replacing the bar
magnet with an iron bar.
4.

Activity 3
Place a bar magnet into the copper coil and move
the bar magnet forward and backward. Observe the
reading of the ammeter.
3.
Answer:
If there are more than one variable in the experimental
design, the results obtained are not conclusive.
Activity 3
Assemble the above experimental set-up.
S
5.
Answer:
Mill’s Method of Difference includes Experimental and
Control groups.
Activity 2
Task 2:
5. What is the precaution of applying the method
(in(4) in the causal reasoning?
Remarks:
1.
N
Task 2
4. Do you know the name of the method (in(3)) of
establishing the casual relationship?

Induction Experiment
Activity 2
Task 2
P 33
Activity 5
Activity 4
Task 3:
Activity 5

3. What is the precaution of applying the method
(in (2)) in causal reasoning?
The Discovery of Radium by Marie Curie.
We should consider and compare as many conditions
and symptoms as possible among the +ve and –ve
groups in order to minimise the chance factor.
was the 5th leading cause of death, and accounted for at least
Air pollution increases hospital
admissions for patients with chronic
obstructive pulmonary disease in
Hong Kong
Answer:
In Hong Kong, Chronic Obstructive Pulmonary Disease (COPD)
4% of all public hospital acute admissions in 2003. The
prevalence of COPD among elderly Chinese (age ≥70 years)
living in Hong Kong is estimated to be 9%. Previous studies
have shown that pulmonary function and quality of life among
patients with COPD were adversely affected by frequent
exacerbations.
Activity 4
Activity 4


In Marie Curie’s time a radioactive substance, uranium was
Activity 5
One day when Marie Curie and his husband were doing research on

discovered. When uranium compound was placed onto a
some samples containing uranium, they discovered that the
was carried out by the Department of Medicine and
photographic plate covered with black paper, it produced
radioactivity measured was far greater than that of uranium. They
Therapeutics and the Department of Community and
an impression analogous to that which light would make on
began to suspect that the sample contained other radioactive active
Family Medicine, the Chinese University of Hong Kong.
that plate. The impression is due to uranium rays that
pollutants (sulphur dioxide [SO2], nitrogen dioxides [NO2],
ozone [O3], particulates with an aerodynamic diameter of
less than 10μm [PM10] and 2.5μm [PM2.5]) and
meteorological variables from January 2000 to December
COPD in Hong Kong.
2004 were obtained from several government departments.
work the couple isolated a very minute quantity of black power,
it behaves like a conductor.
Data of daily emergency hospital admissions to 15 major
hospitals in Hong Kong for COPD and indices of air
ambient air pollutants and the hospitalisation rate due to
for the unknown radioactive substance. Finally, after 45 months’ hard
can discharge an electroscope by making the air surrounds

This study assessed the relationship between the levels of
substances. Then they carried out numerous experiments to search
traverse the paper. These same rays are like X-rays, which
Activity 5
A study has just been published in the journal THORAX
radium chloride in 1902.
Activity 5
Task 4
Task 4
1.Show the logic (method) in the cause of the
discovery of radium by Marie Curie.
1.Show the logic (method) in the cause of the
discovery of radium by Marie Curie.
Answer:
Symbolically, the Method of residues can be represented as:
A B C occur together with x y z
B is known to be the cause of y
C is known to be the cause of z
Therefore A is the cause of x
e.g.
1. Let A be Uranium and “a” be the radioactivity measured
due to the effect of A
2. Let B be the unknown radioactive substance and “b” be the
radioactivity measured due to the effect of B.
3. Since the radioactivity measured was higher than expected
(a+b>a), then the source of the radioactivity must come
from radioactive substance(s) other than A.
2. Do you know the name of the method (in
(1)) of establishing causal relationship?
3. What is the precaution of applying the
method (in (2)) in causal reasoning?
Task 4
Task 4
3. What is the precaution of applying the method (in
(2)) in causal reasoning?
2. Do you know the name of the method (in (1)) of
establishing the causal relationship?
Answer:
Answer:

The induction method is called Method of Residues.

P 34
Only when it is clear that certain part of the
phenomenon or observation is due to some recognized
reason/factors, can the factor/reason that can account
for the remaining part of the observation/phenomenon
be confirmed.
Sometimes it is difficult to use the Method of Residue to
find the causal relationship because the remaining
factor found is a compound factor. As in the discovery
of radium, Marie Curie first isolated Po (plutonium) and
then found radium which contributed to the major
difference in the observed radioactivity of the uranium
sample.

Activity 5
Significant associations were found between hospital

admissions for COPD with all 5 air pollutants. For every
Adverse effects of ambient concentrations of air
10μg/m3 increase in SO2, NO2, O3, PM10 and PM2.5, there
pollutants on hospitalization rates for COPD are
was 0.7%, 2.6%, 3.4%, 2.4% and 3.1% increases in the
evident, especially during the winter season in Hong
rates of COPD hospitalizations respectively. O3 had the
Kong. Measures to improve air quality are urgently
strongest effect on COPD hospitalizations. The effect of SO2,
needed.
NO2, and O3 had a stronger effect on COPD admissions in the
cold season (December to March) than during the warm
season.
(Press Release of CUHK 6 March 2007)
Task 5
1.
Task 5
Use one or two sentences to describe the findings
1.
of the Chinese University of Hong Kong?
2.
the Chinese University of Hong Kong?
Please use a table/diagram to represent the logic
in establishing the causal relationship. Do you
Answer:
Air Pollution Increases Hospital Admissions for
Patients with Chronic Obstructive Pulmonary
Disease in Hong Kong.
know the name of the method (in (2)) of
establishing such causal relationship?
3.
Use one or two sentences to describe the findings of
What is the precaution of applying the method (in
(2)) in causal reasoning?
P 35
Teachers’ Reference
Task 5
Task 5
Case/event Circumstance Effect
1
A, B, C
x
2
A+, D, E
X+
3
A-, F, G
X-

Concomitant Variation
Learning Objectives
Students will:
 gain an understanding of Mill’s Method in causal reasoning;
 be able to use Mill’s method to analyze and interpret observations for the purpose of drawing
conclusions about the causal relationships they exhibit;
 be able to understand the limitations of Mill’s method in causal reasoning.
Evidence:There is a direct correlation between the degree to which the
cause occurred and the degree to which the effect occurred.
Conclusion: A and x has a causal relationship. A is the cause of x.
Suggested Lesson Time: 90 minutes
Task 5
a)
b)
c)
d)
Make observations
Two events have correlation but it is not
necessary for them to have causal relationship.
For instance, many overweight people would die
at young ages. However, overweight is not a
direct cause of early death.
Many irrelevant factors would increase or
decrease concomitantly. For instance, both of
the average rain falls per year and the birth
rates in Hong Kong have been decreasing. It is
not likely that the amount of rainfall affects the
birth rate.
There is a limit to degree of change in
circumstance and effect
The circumstance must be the only cause for
the effect
Method of Difference
求異法
Joint method of
Agreement and
Difference
求同求異並用法
Method of Concomitant
Variation
共變法
Lesson 2 Causal Inference-Mill’s Method in Causal Reasoning
Analyse and interpret the observations
Draw conclusions about the causal relationships
Activity 1(a)
Disease X was recorded long time ago. People with disease X have shaking chills at regular time
intervals (usually at mid-day between 11 a.m. to 12 noon), followed by high fever lasting for 2 to
6 hours. The patients may also have other symptoms like headaches, vomiting, delirium, anxiety
and restlessness.
It was also discovered that the blood of the infected patients contained a micro-organism that was
a new species of parasite at that time.
Some doctors also observed that
 people sleeping outdoors were more susceptible to get the disease that those of sleeping
indoors;
 people sleeping near a camp fire were less susceptible to get the disease.
Method of Agreement
求同法
What are your
comments on
Mill‛s Methods of
causal reasoning?
Mill’s methods in
caus al reas oning
Method of Residues
剩餘法
Mill’s methods of causal reasoning
Mill’s methods of causal reasoning
Discovery or Proof ?
Confirmation
- as tools for confirming
hypotheses
- useful if we have already
proposed several specific
hypotheses about what may be the
cause of an observed event
- can’t be used to discover the
cause of some observed event
- can only be used to establish the
correlation between the occurrences
of distinct events
P 36
A doctor (Dr. R) made a lot of efforts in researching Disease X. He observed that disease X was
widely spread in the following areas in 1895:
Place Natural Environment
A
Near a river
B
Inside a forest
C
Near the marshes
D
Paddy fields
P 37
Dr. R also observed that there were a lot of mosquitoes in places A, B, C and D. He suggested that
mosquitoes might be responsible for the transmission of the micro-organisms that caused Disease
X.
Task 1(a):
1. Use flow charts / comparison tables / diagrams to illustrate how Doctor R arrived at his
proposition that mosquitoes might be responsible for the transmission of the micro-organisms
that cause Diseased X.
Place
Circumstance
Disease X
A (Near a river)
Water + mosquitoes +
+
plants P1, P2, P3 … +
animals A1, A2, A3 …
B (Inside a forest)
Water + mosquitoes +
+
plants P1, P2, P3, P4 …
+ animals A1, A2, A3,
A4 …
C (Near the marshes)
Water + mosquitoes +
+
plants P1, P2, P3, P4, P5
… + animals A1, A2,
A3, A4, A5 …
D (Paddy fields)
Water + mosquitoes +
+
plants P1, P2, P3, P4, P5,
P6 … + animals A1, A2,
A3, A4, A5, A6 …
=> Either water or mosquitoes may be related to Disease X
With reference to the observation of some doctors, it is more likely for mosquitoes to spread
Disease X.
Remarks:
After years of hard work on researching Disease X, Dr. R discovered that mosquitoes were the
carriers of the parasite, which caused Disease X and such a great discovery has led Dr. R to get the
Nobel Prize in Medicine in 1902. Disease X is Malaria and Dr. R was Ronald Ross.
2. Use simple diagrams to show the logic of the causal relationship in case 1(a).
Event/Case
Circumstance
Effect
1
E, R, Y, Z
e, r, y, z
2
E, P, Q, T
e, p, q, t
3
E, H, J, K
e, h, j, k
4
E, L, M, N
e, l, m, n
=> E and e has a causal relationship
P 38
Remarks:
Mill’s Method of Agreement: investigation of the cases in which the effect occurred revealed
only one prior circumstance that all of them shared.
Activity 1(b)
In an uneventful afternoon, four students of School A suffered from severe diarrhea. All
of them went to the hospital and the doctor naturally suspected that the symptom might be
related to the food eaten by the students during lunch.
The doctor asked the students what they ate for lunch and their answers were as follows:
Student
1
2
3
4
Food items
pizza, orange juice, cookie, vegetable salad
hot dog, French fries, vegetable salad, iced tea
pizza, vegetable salad, coca cola, cheese cake
hamburger, orange juice, vegetable salad, cheese cake
Task 1(b)
1. Use a table / diagram to show the logic of the possible cause of diarrhea among the
students.
Case/event
1
2
3
4
Circumstance
B, C, D, A
E, F, A, G
B, A, H, I
J, C, A, I
Effect
x
x
x
x
Conclusion: A is the cause of x
2. Do you know the name of this method of establishing the causal relationship?
Mill’s Method of Agreement (求同法)
3. What is the precaution of applying the method (in (2)) in causal reasoning?
You may get the answer “vegetable salad” from the method of agreement. But
pathology tests showed that there were no bacteria causing diarrhea found in the
vegetable salad. The actual cause why these four students suffered from diarrhea
was that the forks they used to eat the vegetable salad were contaminated with
bacteria.
People will be blinded by apparent causal relationship but in fact there are real reasons
other than that of observed. For instance, in the malaria case above, people believed that
the cause of malaria was marsh but the true reasons are that the parasites that cause malaria
can be carried by mosquitoes that breed in water.
P 39
Activity 2:
Michael Faraday’s Experiment
3. Use a comparison table / diagram to show the logic of the discovery by Faraday.
Case/event
1
2
copper coil
A
ammeter
1. Assemble the above experimental set-up.
Circumstance
A, B, C
- B, C
Effect
x
-
Conclusion:A is the cause of x
4. Do you know the name of the method (in (3)) of establishing the causal
relationship?
Mill’s Method of Difference (求異法)
2. Place a bar magnet into the copper coil (no movement of the magnet) and
observe the reading of the ammeter.
Remarks: Mill’s Method of Difference includes Experimental and Control groups.
3. Place a bar magnet into the copper coil and move the bar magnet forward and backward. Observe the reading of the ammeter.
5. What is the precaution of applying the method (in (4)) in the causal reasoning?
If there are more than one variables in the experimental design, the results
obtained are not conclusive.
4. Repeat steps (3) and (4) by replacing the bar magnet with an iron bar.
Task 2:
1. Design a table to record the results of the above experiment.
Movement of magnet
Yes
No
Movement of the pointer of ammeter
Yes
No
Movement of iron
Yes
No
Movement of ammeter
No
No
2. Suggest the cause of change (if any) in Faraday’s Experiment.
It’s the movement of the magnet that causes the pointer of the ammeter to move.
Conclusion: Change of magnetic field causes generation of electricity.
P 40
P 41
Activity 3
Dr. Sun Simiao (孫思邈) (AD 581-682) was a very famous doctor in Tang Dynasty.
There were several rich people living in the capital of China, Changon. All of them
were suffered from a strange disease at the same time and they all had similar
symptoms, including leg edema, muscle pain, fatigue and tiredness. All the famous
doctors could not treat the diseases.
Dr. Sun was invited to treat one of the patients. He went to the kitchen of one of the
rich patients. The cook told him that his master did not like to eat too much meat
or fish but he liked to eat polished rice (white rice which had been polished several
times). Dr. Sun also paid visits to several rich patients who suffered from the same
diseases. He found that these patients had a similar habit of eating polished rice.
He then noted that the diseases were not found among the poor people who ate
coarse rice. He concluded that the cause of the disease was related to the eating of
polished rice. He then asked the patients to eat coarse rice instead. Luckily, all the
patients were cured within half a month.
Task 3:
1. Use a table / diagram to show the logic of the discovery of the cause of the
disease.
Case
Patient A
(rich) (+ve gp)
Patient B
(rich) (+ve gp)
C
(poor) (-ve gp)
D
(poor) (-ve gp)
Conditions
Symptom
Activity 4
THE DISCOVERY OF RADIUM by Marie Curie
In Marie Curie’s time a radioactive substance, uranium was discovered. When
uranium compound was placed onto a photographic plate covered with black paper,
it produced an impression analogous to that which light would make on that plate.
The impression is due to uranium rays that traverse the paper. One day when Marie
Curie and his husband were doing research on some samples containing uranium,
they discovered that the radioactivity measured was far greater than that of uranium.
They began to suspect that the sample contained other radioactive active substances.
Then they carried out numerous experiments to search for the unknown radioactive
substance. Finally, after 45 months’ hard work the couple isolated a very minute
quantity of black power, radium chloride in 1902.
1. Show the logic (method) in the cause of the discovery of radium by Marie Curie. Symbolically, the Method of residues can be represented as:
A, B, C occur together with x, y, z
B is known to be the cause of y
C is known to be the cause of z
Therefore, A is the cause of x.
e.g.
Let A be Uranium and “a” be the radioactivity measured due to the effect of A.
Let B be the unknown radioactive substance and “b” be the radioactivity measured
due to the effect of B.
Since the radioactivity measured was higher than expected (a+b>a), then the source
of the radioactivity must come from radioactive substance(s) other than A.
W
X
Y
(ate polished
rice)
Yes
No
Yes
Yes
No
No
Yes
Yes
Yes
No
No
No
2. Do you know the name of the method (in (1)) of establishing the causal
relationship?
The induction method is called Method of Residues.
No
Yes
No
No
3. What is the precaution of applying the method (in (2)) in causal reasoning?
leg edema, muscle pain,
fatigue and tiredness
2. Do you know the name of the method (in (1)) of establishing the causal relationship?
Mill’s Joint Method of Agreement and Difference (求同求異並用法)
3. What is the precaution of applying the method (in (2)) in causal reasoning?
We should consider and compare as many conditions and symptoms as possible among the +ve and –ve groups in order to minimise the chance factor.
P 42
Sometimes it is difficult to use the Method of Residue to find the causal relationship
because the remaining factor found is a compound factor. As in the discovery of
radium, Marie Curie first isolated Po (plutonium) and then found radium which
contributed to the major difference in the observed radioactivity of the uranium
sample.
P 43
Activity 5
2. Please use a table/diagram to represent the logic in establishing the causal
relationship.
Air Pollution Increases Hospital Admissions for Patients
with Chronic Obstructive Pulmonary Disease in Hong Kong
In Hong Kong, Chronic Obstructive Pulmonary Disease (COPD) was the 5th leading
cause of death, and accounted for at least 4% of all public hospital acute admissions
in 2003. The prevalence of COPD among elderly Chinese (age ≥70 years) living
in Hong Kong is estimated to be 9%. Previous studies have shown that pulmonary
function and quality of life among patients with COPD were adversely affected by
frequent exacerbations.
A study has just been published in the journal THORAX and was carried out by the
Department of Medicine and Therapeutics and the Department of Community and
Family Medicine of the Chinese University of Hong Kong and. This study assessed
the relationship between the levels of ambient air pollutants and the hospitalisation
rate due to COPD in Hong Kong.
Data of daily emergency hospital admissions to 15 major hospitals in Hong Kong
for COPD and indices of air pollutants (sulphur dioxide [ SO2 ], nitrogen dioxides
[NO2 ], ozone [ O3 ], particulates with an aerodynamic diameter of less than 10 μ m
[PM10] and 2.5 μ m [PM2.5]) and meteorological variables from January 2000 to
December 2004 were obtained from several government departments.
Significant associations were found between hospital admissions for COPD with all
3
five air pollutants. For every 10mg/ m increase in SO2 ,NO2 , O3 , PM10 and PM2.5,
there was 0.7%, 2.6%, 3.4%, 2.4% and 3.1% increases in the rates of COPD
hospitalisation respectively. O3 had the strongest effect on COPD hospitalisation.
The effect of SO2 ,NO2 and O3 had a stronger effect on COPD admissions in the cold
season (December to March) than during the warm season.
Adverse effects of ambient concentrations of air pollutants on hospitalisation rates
for COPD are evident, especially during the winter in Hong Kong. Measures to
improve air quality are urgently needed.
Case/event
1
2
3
Circumstance
A, B, C
A+, D, E
A-, F, G
Effect
x
x+
x-
Evidence: There is a direct correlation between the degree to which the cause occurred
and the degree to which the effect occurred.
Conclusion:A and x has a causal relationship
A is the cause of x
3. The name of the above method in causal reasoning is called Method of
Concomitant Variation.
4. What is the precaution of applying the method (in (2)) in causal reasoning?
(a). Two events have correlation but it is not necessary for them to have causal
relationship. For instance, many overweight people would die at young ages.
However, overweight is not a direct cause of early death.
(b). Many irrelevant factors would increase or decrease concomitantly. For
instance, both of the average rain falls per year and the birth rates in Hong
Kong have been decreasing. It is not likely that the amount of rainfall affects
the birth rate.
(c). There is a limit to degree of change in circumstance and effect.
(d). The circumstance must be the only cause for the effect.
(Press Release of CUHK 6 March 2007)
Task 5:
1. Use one or two sentences to describe the findings of the Chinese University of
Hong Kong?
Air Pollution Increases Hospital Admissions for Patients with Chronic
Obstructive Pulmonary Disease in Hong Kong.
P 44
P 45
Students’ Worksheet
Task 1(a):
1. Use flow charts / comparison tables / diagrams to illustrate how Doctor R
arrived at his proposition that mosquitoes might be responsible for the
transmission of the micro-organisms that cause Diseased X.
Lesson 2 Causal Inference
Activity 1(a)
Disease X was recorded long time ago. People with disease X would have shaking
chills at regular time intervals (usually at mid-day between 11 a.m. to 12 noon),
followed by high fever lasting for 2 to 6 hours. The patients may also have symptoms
like headaches, vomiting, delirium, anxiety and restlessness.
It was also discovered that the blood of the infected patients contained a microorganism that was a new species of parasite at that time.
Some doctors also observed that
 people sleeping outdoors were more susceptible to get the disease that those
sleeping indoors;
 people sleeping near a camp fire were less susceptible to get the disease.
A doctor (Dr. R) made a lot of efforts in researching Disease X. He observed that
Disease X was widely spread in the following areas in 1895:
Place
A
B
C
D
Natural Environment
Near a river
Inside a forest
Near the marshes
Paddy fields
2. Use simple diagrams to show the logic of the causal relationship in case 1(a).
Dr. R also observed that there were a lot of mosquitoes in places A, B, C and D. He
suggested that mosquitoes might be responsible for the transmission of the microorganisms that caused Disease X.
P 46
P 47
Activity 1(b)
In an uneventful afternoon, 4 students of school A suffered from severe diarrhea.
All of them went to the hospital and the doctor naturally suspected that the symptom
might be related to the food eaten by the students during lunch.
The doctor asked the students what they had eaten for lunch and their answers were
as follows:
Student
1
2
3
4
Food items
pizza, orange juice, cookie, vegetable salad
hot dog, French fries, vegetable salad, iced tea
pizza, vegetable salad, coca cola, cheese cake
hamburger, orange juice, vegetable salad, cheese cake
Task 1(b)
1. Use a table / diagram to show the logic of the possible cause of diarrhea among
the students.
Activity 2:
Michael Faraday’s Experiment
copper coil
A
ammeter
1. Assemble the above experimental set-up.
2. Place a bar magnet into the copper coil (no movement of the magnet) and
observe the reading of the ammeter.
3. Place a bar magnet into the copper coil and move the bar magnet forward and backward. Observe the reading of the ammeter.
4. Repeat steps (3) and (4) by replacing the bar magnet with an iron bar.
2. Do you know the name of this method of establishing the causal relationship?
Task 2:
1. Design a table to record the results of the above experiment.
2. Suggest the cause of change (if any) in Faraday’s Experiment.
3. Use a comparison table / diagram to show the logic of the discovery by Faraday.
3. What is the precaution of applying the method (in (2)) in causal reasoning?
4. Do you know the name of the method (in (3)) of establishing the causal
relationship?
5. What is the precaution of applying the method (in (4)) in the causal reasoning?
P 48
P 49
Activity 3
2. Do you know the name of the method (in (1)) of establishing the causal
relationship?
Dr. Sun Simiao (孫思邈) (AD 581-682) was a very famous doctor in Tang Dynasty.
There were several rich people living in the capital of China, Changon. All of them
were suffered from a strange disease at the same time and they all had similar
symptoms, including leg edema, muscle pain, fatigue and tiredness. All the famous
doctors could not treat the diseases.
3. What is the precaution of applying the method (in (2)) in causal reasoning?
Dr. Sun was invited to treat one of the patients. He went to the kitchen of one of the
rich patients. The cook told him that his master did not like to eat too much meat
or fish but he liked to eat polished rice (white rice which had been polished several
times). Dr. Sun also paid visits to several rich patients who suffered from the same
diseases. He found that these patients had a similar habit of eating polished rice.
He then noted that the diseases were not found among the poor people who ate
coarse rice. He concluded that the cause of the disease was related to the eating of
polished rice. He then asked the patients to eat coarse rice instead. Luckily, all the
patients were cured within half a month.
Task 3:
1. Use a table / diagram to show the logic of the discovery of the cause of the
disease.
P 50
P 51
Activity 5
Activity 4
THE DISCOVERY OF RADIUM by Marie Curie
In Marie Curie’s time a radioactive substance, uranium was discovered. When
uranium compound was placed upon a photographic plate covered with black paper,
it produced on that plate an impression analogous to that which light would make.
The impression is due to uranium rays that traverse the paper. These same rays
can, like X-rays, discharge an electroscope, by making the air which surrounds it a
conductor.
One day when Marie Curie and his husband were doing research on some samples
containing uranium, they discovered that the radioactivity measured was far greater
than that of uranium. They began to suspect that the sample contained other radioactive
active substances. They began to carry out numerous experiments to search for the
unknown radioactive substance. Finally, after 45 months’ hard work the couple
isolated very minute quantity of a black power, radium chloride in 1902.
Task 4
1. Show the logic (method) in the cause of the discovery of radium by Marie Curie.
2. Do you know the name of the method (in (1)) of establishing causal
relationship?
3. What is the precaution of applying the method (in (2)) in causal reasoning?
Air Pollution Increases Hospital Admissions for Patients
with Chronic Obstructive Pulmonary Disease in Hong Kong
In Hong Kong, Chronic Obstructive Pulmonary Disease (COPD) was the 5th leading
cause of death, and accounted for at least 4% of all public hospital acute admissions
in 2003. The prevalence of COPD among elderly Chinese (age ≥70 years) living
in Hong Kong is estimated to be 9%. Previous studies have shown that pulmonary
function and quality of life among patients with COPD were adversely affected by
frequent exacerbations.
A study has just been published in the journal THORAX and was carried out by the
Department of Medicine and Therapeutics and the Department of Community and
Family Medicine of the Chinese University of Hong Kong and. This study assessed
the relationship between the levels of ambient air pollutants and the hospitalisation
rate due to COPD in Hong Kong.
Data of daily emergency hospital admissions to 15 major hospitals in Hong Kong for
COPD and indices of air pollutants (sulphur dioxide [ SO2 ], nitrogen dioxides
[NO2 ], ozone [ O3 ], particulates with an aerodynamic diameter of less than 10 μ m
[PM10] and 2.5 μ m [PM2.5]) and meteorological variables from January 2000 to
December 2004 were obtained from several government departments.
Significant associations were found between hospital admissions for COPD with all
3
five air pollutants. For every 10mg/ m increase in SO2 ,NO2 , O3 , PM10 and PM2.5,
there was 0.7%, 2.6%, 3.4%, 2.4% and 3.1% increases in the rates of COPD
hospitalisation respectively. O3 had the strongest effect on COPD hospitalisation.
The effect of SO2 ,NO2 and O3 had a stronger effect on COPD admissions in the cold
season (December to March) than during the warm season.
Adverse effects of ambient concentrations of air pollutants on hospitalisation rates
for COPD are evident, especially during the winter in Hong Kong. Measures to
improve air quality are urgently needed.
P 52
(Press Release of HKCU 6 March 2007)
P 53
Task 5:
Supplementary Notes
1. Use one or two sentences to describe the findings of the Chinese University of
Hong Kong?
Lesson 2 Causal Inference- Mill’s Methods of causal reasoning
1.
Method of Agreement
Case/event
1
2
3
2. Please use a table/diagram to represent the logic in establishing the causal
relationship.
Circumstance
A, B, C
A, D, E
A, F, G
Effect
x
x
x
Conclusion:A is the cause of x
2.
Method of Difference
Case/event
1
2
Circumstance
A, B, C
- B, C
Effect
x
-
Conclusion:A is the cause of x
Remarks: Mill’s Method of Difference includes Experimental and Control groups
3. The name of the above method in causal reasoning is called _______________.
4. What is the precaution of applying the method (in (2)) in causal reasoning?
3.
Joint Method of Agreement and Difference
Positive
group
Negative
group
Comparison
Case/event
1
2
3
1
2
3
Positive group
Negative group
Circumstance
A, B, C
A, D, E
A, F, G
- B, M
- D, N
- F, O
If “A” is present,
then “x” will occur.
If “A” is absent,
then “x” will not occur.
Conclusion: A is the cause of x.
P 54
P 55
Effect
x
x
x
-
4.
Method of Residues
Pattern of reasoning:
Many elements of a complex effect are shown to result, by reliable causal beliefs,
from several elements of a complex cause, whatever remains of the effect must then
have been produced by whatever remains of the cause.
Symbolically, the Method of Residues can be represented as:
A, B, C occur together with x y z
B is known to be the cause of y
C is known to be the cause of z
Therefore, A is the cause of x.
e.g Let A be Uranium and “a” be the radioactivity measured due to the effect of A.
Let B be the unknown radioactive substance and “b” be the radioactivity measured
due to the effect of B.
Since the radioactivity measured was higher than expected (a+b>a), then the source
of the radioactivity must come from radioactive substance(s) other than A.
5.
Limitations of using Mill’s five methods of causal reasoning to establish causal relationship
in science?
Mill’s Method of causal reasoning
Method of Agreement
2.Cannot observe all possible cases
Method of Difference
If there are more than one variable in the
experimental design, the results obtained are not
conclusive.
Joint Method of Agreement and
Difference
Should observe more cases to minimise the chance
factor, otherwise cannot avoid co-incidence or
unrelated situations
Method of Residues
Sometimes it is difficult to use the Method of
Residue to find the causal relationship because the
remaining factor found is a compound factor. As in
the discovery of radium, Marie Curie first isolated
Po (plutonium) and then found radium which
contributed to the major difference in the observed
radioactivity of the uranium sample.
Method of Concomitant Variation
1. Two events have correlation but it is not
necessary for them to have causal relationship. For
instance, many overweight people would die at
young ages. However, overweight is not a direct
cause of early death.
Method of Concomitant Variation
Case/event
1
2
3
Circumstance
A, B, C
A+, D, E
A-, F, G
Effect
x
x+
x-
Evidence: There is a direct correlation between the degree to which the cause
occurred and the degree to which the effect occurred.
Conclusion:A and x has a causal relationship.
A is the cause of x.
Limitations
1.People will be blinded by apparent causal
relationship but in fact there are real reasons other
than that of observed.
2. Many irrelevant factors would increase or
decrease concomitantly. For instance, both the
average rain falls per year and the birth rates in
Hong Kong have been decreasing. It is unlikely
that the amount of rainfall affects the birth rate.
3. There is a limit to degree of change in
circumstance and effect.
4. The circumstance must be the only cause for the
effect.
P 56
P 57
Suggested Learning and Teaching Activities
Lesson 3Testing a Hypothesis
Student presentation: Actvity 1a
Snapshots of Lesson 2
Causal Inference-Mill’s Methods
Level of Students: S.1-S.2
Suggested Lesson Time: 90 min.
Learning Objectives:
Students will:
 have an understanding of how to test a hypothesis;
 be able to evaluate a hypothesis based on existent information/data.
Materials and Apparatus for each group:
A4 paper for drawing mind-map
Bell-jar
Candles (tall, medium, short)
Gas lighter
Students’ presentation on Activity 2
(Method of Difference)
Teacher’s comment on
Activity 1a & 1b
(Method of Agreement)
Prior knowledge of students:
Students learnt basics of scientific investigation in S.1. The teacher can ask a few
simple questions on how to test a hypothesis to get a general view on students’
knowledge on testing hypotheses.
Students doing Activity 2:
Michael Faraday’s experiment
(Method of Difference)
Students’ presentation on Activity 3
(Joint Method of Agreement & Difference)
Students’ presentation on Activity 5
Method of Concomitant Variation)
Students’ presentation on Activity 4
(Method of Residues)
P 58
Suggested Learning and
Teaching Activities:
Lesson 3 Testing a
Hypothesis
Time
Remarks
allocation
Approx. The students are divided into groups of 4-5 members
90 min.
to carry out the activities.
Activity 1
(Ignaz Semmelweis’
Discovery to the cause of
Childbed Fever)
30 min.
(a). The focus of this activity is to let students
rediscover the cause of Childbed Fever by Doctor
Ignaz Semmelweis in 1840s and let them go through
his process of testing hypotheses based on existent
information/data.
(b). The criteria that can be used in making judgments
about the reliability of a hypothesis to a scientific
explanation include:
• Relevance
• Testability & falsifiability
• Compatibility with known science concepts/laws/
principles
• Good Predictive Power
• Simplicity (the “Occam’s razor” principle)
P 59
Activity 2
(Candle experiment)
40 min.
(a). The focus of this activity is
to let students use P-O-E method
(Predict-Observe-Explain) to do
a scientific investigation first.
PowerPoint
Activity 1
Enhancing Thinking Skills in
Science Context
(b). Then the students are further
required to suggest a hypothesis
to explain the observation.
Part I of
Ignaz Semmelweis’ Discovery to
the cause of Childbed Fever
Lesson 3
Testing a Hypothesis
(c). They also need to list the
steps to test their hypothesis.
Activity 3
(Logic of testing a
hypothesis)
20 min.
The focus of this activity is to
let students understand type
1 and type 2 hypotheses and
their contribution to hypothesis
testing.

Ignaz Semmelweis was a doctor who worked in an Italian
Year
Hospital in 1840s. He noticed that many women died
Death rate of
maternity
patients after
child birth in
the first ward
shortly after childbirth in the ward (first ward) he and his
colleagues were working. He called this phenomenon as
“childbed fever” (產褥熱).

He observed that the death rate due to childbed fever in
the first ward was higher than that of the second ward
Death rate of
maternity
patients after
child birth in
the second
ward
2.3%
1844
8.2%
1845
6.8%
2.0%
1846
11.4%
2.7%
attended only by midwifery students (Ignaz Semmelweis
and other doctors did not help with the delivery of
maternity patients in this ward) in the hospital for 3
consecutive years. The death rates of the maternity
patients in the first and second ward of the hospital were
as follows:
(Reference: Carl G. Hempel (1966))

There were some hypotheses suggested to
Hypothesis I: Atmospheric Change Hypothesis
explain the above observations.

You will be divided into groups of 4-5 students.

Each group will be required to discuss the

possibility of the different hypotheses.

You are required to write down your
discussion result in the form of a mind map.

You may get further information on each
hypothesis from the teacher after completion
of the mind map.
P 60
P 61
The cause of the higher rate of childbed
fever is due to atmospheric-cosmic changes
(大氣變化).
Task 1:

Hypothesis 2: Crowdedness Hypothesis
What other information do you need to know before you

agree or disagree with this hypothesis? Write down
your discussion result with the aid of a mind map.

The cause of the higher rate of childbed
fever is due to crowdedness in the first
ward.
Task 2 (Your teacher will give you further information


after you have completed task 1)

Part III of Ignaz Semmelweis’ Discovery
to the Cause of Childbed Fever
Testing of his own Hypothesis:
Semmelweis thought that it was the cadaveric
matter in the corpse that entered the blood of
professor Kolletschka infecting him with childbed
fever.

cadaveric matterscalpel blood of professor
Kolletschka childbed feverdeath

Can this hypothesis be used to explain Semmelweis’

findings?

Semmlweis then instituted a strict policy in the first
ward. Semmlweis, his colleagues and medical
students used chlorinated lime (bleaching powder)
to wash their hands prior to attending patients.
The death rate of maternity patients dropped from
18.3% to 1.3% in 1848 and was even lower than
that of the second ward (death rate: 1.33%).
We call the cadaveric matter ‘bacteria’ nowadays.
Explain your answer.
Hypothesis 4:
“Position In Delivery” Hypothesis
Hypothesis 3:
“Rude Manner In Examination” Hypothesis
Activity 2:
Activity 2:
Reference: Learning from TIMSS (2006)

The cause of the higher rate of childbed
fever in the first ward was due to the rude
manner of medical students when they
examined the pregnant mothers between
deliveries.

The cause of the higher rate of childbed
fever in the first ward was due to the
supine position (lying flat on the back, face
upwards) of pregnant mothers in delivery.
Procedure:
(a)Light up three candles of different lengths (tall, medium,
short).
(b)Predict the going out sequence of the candle flame when
the three burning candles are covered with a bell jar as
shown in the diagram below:
(c) Cover the three burning candles with a bell jar.
(d) Observe what happens and write down the results.
Part II of Ignaz Semmelweis’ Discovery
to the cause of Childbed Fever

Group Discussion
One colleague of Semmelweis, professor Kolletschka
cut his own finger with a scalpel by accident when
he was performing an autopsy. Such accidents
happened quite often among doctors between
deliveries. Professor Kolletschka developed
symptoms similar to childbed fever later and died.
P 62
a.
If you were Semmelweis, what would you think? (any
causal relationship between the accident and Professor
Kolletschka’s death)
b.
Can you suggest a hypothesis to explain his death?
c.
What evidence was needed to support the hypothesis in
(b)?
Activity 2:

Suggest a hypothesis to explain the above
observation. Write down the steps to test your
hypothesis. Then carry out the experiment if
possible and see whether your hypothesis is right
or wrong. If it is wrong, you need to think of a
new hypothesis and test it again.
P 63
Illustration of Type I Hypothesis





Write down the logic of testing a hypothesis
(Home Assignment).

Implication: People would be infected with virus X if they talk to
each other.

Observation / Result: It is found that it is not the case that people
became infected with virus X after talking to each other.

Observation: The streets are wet.
Conclusion: Therefore, dogs urinated.
The flame of the tallest candle would go out first, then the medium size and finally
the shortest one.

The reason is that burning of the candles would produce carbon dioxide and the
heat evolved would heat up carbon dioxide that rise upwards due to smaller density.
The accumulation of a large amount of carbon dioxide at the top of the bell jar
would put out the candle flame of the tallest candle first.
Activity 3
Hypothesis: If dogs urinates in the street,
then the streets are wet.

Remarks:
Remarks 1: The above argument does not
prove that dogs urinated. It might be the
case but might be some naughty boy did so.
Remarks 2: Type 2 pattern of reasoning
affirms the consequent implication. If the
observation in Type 2 Hypothesis occurs, the
hypothesis will be supported. However, the
arguments in type 2 are not deductively valid.
Type 1 Hypothesis
Suggested answers:
We can test scientific hypotheses by considering
their implications and then use experiments or
observation to test those implications.
Let H be the hypothesis and I be the
implication.
P 64

If H is right, then I would happen. (If H, then I)

I is not observed.
(Not I )

So H is not right.
(So, not H)
If H is right, then I would happen.
(If H, then I)
I is observed. (I )
So H is right. (So, H)
The observation and experiment in Type 1 Hypothesis refute the
hypothesis. Deduction is widely used in scientific reasoning.



Hypothesis: Virus X would infect people through air transmission
Illustration of Type 2 Hypothesis
Activity 3

Type 2 Hypothesis
P 65

Scientists always put up a hypothesis, deduce
implications from the hypothesis, test the implications by
experiments and find out whether the experimental result
confirms or refutes the hypothesis.

Due to the reason as exemplified by illustration of Type 2
Hypothesis scientists can never be 100 percent certain
that a scientific hypothesis is true. Scientific conclusions
are always tentative and open to revision or correction.
However, scientific conclusions can be affirmed with a
high degree of confidence by means of carefully controlled
experiments.
Teachers’ Reference
Year
Lesson 3 Testing a Hypothesis
Learning Objectives
Students will:
 have an understanding of how to test for a hypothesis;
 be able to evaluate a hypothesis based on existent information/data.
Focus ideas:
It is difficult to prove the truth of a scientific hypothesis but it is possible to compare
the distinct hypotheses involved in rival explanations of the same event. The
criteria that can be used in making judgments about the reliability of a hypothesis to
a scientific explanation include:
• Relevance
• Testability
• Compatibility with known science concepts/laws/principles
• Good Predictive Power
• Simplicity
Activity 1
Part I of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
Ignaz Semmelweis was a doctor who worked in an Italian Hospital in 1840s. He
noticed that many women died shortly after labouring in the ward (first ward) he
and his colleagues were working. He called this phenomenon as “childbed fever”
(產褥熱). He observed that the death rate due to childbed fever in the first ward
was higher than that of the second ward attended only by midwifery students (Ignaz
Semmelweis and other doctors did not help with the delivery of maternity patients
in this ward) in the hospital for 3 consecutive years. The death rates of the maternity
patients in the first and second ward of the hospital were as follows:
Death rate of maternity
patients after child birth in
the first ward
1844
8.2%
1845
6.8%
1846
11.4%
(Reference: Carl G. Hempel (1966))
Death rate of maternity
patients after child birth in
the second ward
2.3%
2.0%
2.7%
There were some hypotheses suggested to explain the above observations. You
will be divided into groups of 4-5 students. Each group will be required to discuss
the possibility of the different hypotheses. You are required to write down your
discussion result in the form of a mind map. You may get further information on
each hypothesis from the teacher after completion of the mind map.
Hypothesis I: Atmospheric Change Hypothesis
The cause of the higher rate of childbed fever is due to atmospheric-cosmic changes
(大氣變化).
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
Task 2
(Your teacher will give you further information after you have completed task 1)
[Further information from teacher: It was found that there were no cases of childbed
fever in nearby hospitals.]
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
Hypothesis 2: Crowdedness Hypothesis
The cause of the higher rate of childbed fever is due to crowdedness in the first
ward.
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
P 66
P 67
Task 2
(Your teacher will give you further information after you have completed task 1)
[Further information from teacher: Actually, the second ward was more crowded
than the first ward since many pregnant mothers were afraid to stay in the first ward
due to the higher death rate.]
Task 2
(Your teacher will give you further information after you have completed task 1)
[Further information from teacher: It was found that the rate of death due to childbed
fever in the first ward was still high when the pregnant mothers lay on one’s side in
delivery.]
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
Hypothesis 3: “Rude Manner In Examination” Hypothesis
The cause of the higher rate of childbed fever in the first ward was due to the rude
manner of medical students when they examined the pregnant mothers between
deliveries.
Part II of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
A colleague of Semmelweis, Professor Kolletschka cut his own finger with a scalpel
by accident when he was performing an autopsy. Such accidents happened quite
often among doctors during deliveries. Professor Kolletschka developed symptoms
similar to childbed fever later and died.
Group Discussion
Task 2
(Your teacher will give you further information after you have completed task 1)
[Further information from teacher:
(i) It was found that the wound due to the rude manner in the examination
between deliveries was usually less serious when compared with the wound
due to the labouring process.
(ii) When the number of medical students was cut to a half, it was found that the
death rate due to childbed fever in the first ward dropped initially but it
eventually increased as high as before.
(a) If you were Semmelweis, what would you think? (any causal relationship
between the accident and Professor Kolletschka’s death)
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
Semmelweis thought that it was the cadaveric matter in the corpse that entered the
blood of Professor Kolletschka infecting him with childbed fever.
Hypothesis 4: “Position In Delivery” Hypothesis
The cause of the higher rate of childbed fever in the first ward was due to the supine
position (lying flat on the back, face upwards) of pregnant mothers in deliveries.
cadaveric matterscalpel
feverdeath
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
P 68
(b) Can you suggest a hypothesis to explain his death?
(c)What evidence was needed to support the cause in (b)?
Part III of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
blood
of
professor
Kolletschka
childbed
Testing of his own Hypothesis:
Semmlweis then instituted a strict policy in the first ward. Semmlweis, his colleagues
and medical students used chlorinated lime water to wash their hands prior to
attending patients. The death rate of maternity patients dropped from 18.3% to
1.3% in 1848 and was even lower than that of the second ward (death rate: 1.33%).
We call the cadaveric matter ‘bacteria’ nowadays.
P 69
Activity 2: (reference: Learning from TIMSS (2006))
Procedure:
(a). Light up three candles of different lengths (tall, medium, short).
(b). Predict the going out sequence of the candle flame when the three burning
candles are covered with a bell jar as shown in the diagram below:
Activity 3
Write down the logic of testing a hypothesis (Home Assignment).
Suggested answers:
Testing the Hypotheses
We can test scientific hypotheses by considering their implications and then use
experiments or observation to test those implications.
Let H be the hypothesis and I be the implication.
Type 1 Hypothesis
1. If H is right, then I would happen. (If H, then I)
2. I is not observed. (Not I )
3. So H is not right. (So, not H)
(c). Cover the three burning candles with a bell jar.
(d). Observe what happens and write down the results.
Remarks:
The flame of the tallest candle would go out first, then the medium size and finally
the shortest one. The reason is that burning of the candles would produce carbon
dioxide and the heat evolved would heat up carbon dioxide that rises upwards due to
smaller density. The accumulation of a large amount of carbon dioxide at the top of
the bell jar would put out the candle flame of the tallest candle first.
(e). Suggest a hypothesis to explain the above observation. Write down the steps
to test your hypothesis. Then carry out the experiment if possible and see
whether your hypothesis is right or wrong. If it is wrong, you need to think of
a new hypothesis and test it again.
P 70
The observation and experiment in Type 1 Hypothesis refute the hypothesis.
Deduction is widely used in scientific reasoning.
Illustration of Type I Hypothesis
Hypothesis: Virus X would infect people through air transmission.
Implication: People would be infected with virus X if they talk to each other.
It is found that it is not the case that people became infected with virus X after
talking to each other.
Type 2 Hypothesis
1. If H is right, then I would happen. (If H, then I)
2. I is observed. (I )
3. So H is right. (So, H)
P 71
Type 2 pattern of reasoning affirms the consequent arguments. The observation
and experiment in Type 2 Hypothesis confirm with the hypothesis H. However, the
arguments in type 2 are not deductively valid.
Illustration of Type 2 Hypothesis
If dogs urinate in the street, then the streets are wet.
The streets are wet.
Therefore, dogs urinated.
The above argument does not prove that dogs urinated. It might be the case but
might be some naughty boy did so.
Scientists always put up a hypothesis, deduce implications from the hypothesis,
test the implications by experiments and find out whether the experimental result
confirms or refutes the hypothesis.
Due to the reason as exemplified by illustration of Type 2 Hypothesis scientists
can never be 100 percent certain that a scientific hypothesis is true. Scientific
conclusions are always tentative and open to revision or correction. However,
scientific conclusions can be affirmed with a high degree of confidence by means of
carefully controlled experiments.
Students’ Worksheet
Lesson 3Testing a Hypothesis
Activity 1
Part I of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
Ignaz Semmelweis was a doctor who worked in an Italian Hospital in 1840s. He
noticed that many women died shortly after childbirth in the ward (first ward) he
and his colleagues were working. He called this phenomenon as “childbed fever”
(產褥熱). He observed that the death rate due to childbed fever in the first ward
was higher than that of the second ward attended only by midwifery students (Ignaz
Semmelweis and other doctors did not help with the delivery of maternity patients
in this ward) in the hospital for 3 consecutive years. The death rates of the maternity
patients in the first and second ward of the hospital were as follows:
Year
Death rate of maternity patients
after child birth in the first ward
1844
1845
1846
8.2%
6.8%
11.4%
(Reference: Carl G. Hempel (1966))
Death rate of maternity patients
after child birth in the second
ward
2.3%
2.0%
2.7%
There were some hypotheses suggested to explain the above observations. You
will be divided into groups of 4-5 students. Each group will be required to discuss
the possibility of the different hypotheses. You are required to write down your
discussion result in the form of a mind map. You may get further information on
each hypothesis from the teacher after completion of the mind map.
Hypothesis I: Atmospheric Change Hypothesis
The cause of the higher rate of childbed fever is due to atmospheric-cosmic changes
(大氣變化).
P 72
P 73
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
Hypothesis 2: Crowdedness Hypothesis
The cause of the higher rate of childbed fever is due to crowdedness in the first
ward.
Task 1:
What other information do you need to know before you agree or disagree on this
hypothesis? Write down your discussion result with the aid of a mind map.
Task 2
(Your teacher will give you further information after you have completed task 1)
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
P 74
Task 2
(Your teacher will give you further information after you have completed task 1)
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(a). Explain your answer.
P 75
Hypothesis 3: “Rude Manner In Examination” Hypothesis
The cause of the higher rate of childbed fever in the first ward was due to the rude
manner of medical students when they examined the pregnant mothers between
deliveries.
Task 1:
What other information do you need to know before you agree or disagree at this
hypothesis? Write down your discussion result with the aid of a mind map.
Task 2
(Your teacher will give you further information after you have completed task 1)
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
P 76
Hypothesis 4: “Position In Delivery” Hypothesis
The cause of the higher rate of childbed fever in the first ward was due to the supine
position (lying flat on the back, face upwards) of pregnant mothers in delivery.
Task 1:
What other information do you need to know before you agree or disagree at this
hypothesis? Write down your discussion result with the aid of a mind map.
Task 2
(Your teacher will give you further information after you have completed task 1)
(a). Can this hypothesis be used to explain Semmelweis’ findings?
(b). Explain your answer.
P 77
Part II of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
One colleague of Semmelweis, professor Kolletschka cut his own finger with a
scalpel by accident when he was performing an autopsy. Such accidents happened
quite often among doctors between deliveries. Professor Kolletschka developed
symptoms similar to childbed fever later and died.
Group Discussion
Activity 2:
(reference: Learning from TIMSS (2006))
Procedure:
(a). Light up three candles of different lengths (tall, medium, short).
(b). Predict the going out sequence of the candle flame when the three burning
candles are covered with a bell jar as shown in the diagram below:
(a) If you were Semmelweis, what would you think? (any causal relationship
between the accident and professor Kolletschka’s death)
(b) Can you suggest a hypothesis to explain his death?
(c)What evidence was needed to support the hypothesis in (b)?
(c). Cover the three burning candles with a bell jar.
(d). Observe what happens and write down the results.
Part III of Ignaz Semmelweis’ Discovery to the cause of Childbed Fever
(Teacher will discuss the final part of the story with the students)
(e). Suggest a hypothesis to explain the above observation. Write down the steps
to test your hypothesis. Then carry out the experiment if possible and see
whether your hypothesis is right or wrong. If it is wrong, you need to think of
a new hypothesis and test it again.
P 78
P 79
Student Products
Activity 3
Write down the logic of testing a hypothesis.
Mind Map of the “Atmospheric Change”Hypothesis
Ignaz Semmelweis’ Discovery to
the cause of Childbed Fever
Mind Map of the “Rude Manner in
Examination” Hypothesis
Mind Map of the “Crowdedness” Hypothesis
Mind Map of the “Position in
Delivery” Hypothesis
P 80
P 81
Suggested Learning and Teaching Activities
Lesson 4Experimental Designs
Level of Students: S.1-S.2
Learning Objectives
Students will:
 have an understanding of the 3 types of causal experiments, Randomized
Design, Prospective Design and Retrospective Design commonly used in
scientific researches;
 be able to identify the type of experimental design being used in the
establishment of causal links;
 be able to know the pros and cons of the 3 types of causal experiments.
Focus ideas:
There are 3 types of causal experiments, Randomized Design, Prospective Design
and Retrospective Design commonly used in scientific researches. Each of them
has pros and cons. We need to be careful when we come across many “research
findings” in the media (e.g. newspaper and the internet). We should be critical about
their experimental designs and interpret the “research findings” with great care.
Suggested Learning
and Teaching
Activities:
Lesson 4
Experimental Designs
Time
Remarks
allocation
Approx.
90 min.
Activity 1
25 min.
(Randomized
Experimental Design)
(a). The focus of this activity is to enhance
students’ understanding of the Randomized
Experimental Design including the
advantages and disadvantages (including
the fact that if a scientist wants to study the
effect of a certain poison on humans, he/
she is not allowed to choose an experimental
and control group at random from a large
population) of the design.
(b). Students need to be reminded about the
importance of selecting samples at random
from a large population, otherwise the results
obtained may not be conclusive.
Activity 2
30 min.
(Prospective
Experimental Design)
(a). The focus of this activity is to let students
understand the application of Prospective
Experimental Design in scientific research
and the pros and cons of the design.
(b). A good prospective design can strongly
indicate a causal link though not as strongly
as can a randomized design.
Activity 3
20 min.
(Retrospective
Experimental Design)
(a).The focus of this activity is to let students
understand the application of Retrospective
Experimental Design in scientific research
and the pros and cons of the design.
(b). Students should note that even the best
retrospective studies provide only weak
evidence for a causal link because other
potential causal factors may influence the
experimental and control group (extremely
difficult to control).
Since students may come across many research findings concerning humans in their
daily life, activities resembling clinical studies are used in this lesson to enhance
students’ motivation to learn.
Suggested Lesson Time: 90 min.
Prior knowledge of students:
Students should have learnt the design of a simple investigation involving dependent
variable, independent variables and control variables. They also know the validity
of an experimental design depends on the construction of a fair test. The teacher
may ask the students a few related questions to check their understanding on such
concepts.
Exercise
P 82
The students are divided into groups of 4-5
members to carry out the activities.
15 min.
P 83
PowerPoint
Enhancing Thinking Skills in Science
Context
Activity 1

Lesson 4
Experimental Design
1.

A scientist, Dr. Chan, wants to design an experiment to
investigate the following topic:
The effect of taking a nap (a short sleep during the day) on
longevity
Activity 2:

Randomised Experimental Design can provide
strong evidence to support an hypothesis because
other possible causal factors are controlled in the
experimental design.
every day) and those who seldom eat fruits (eating fruits less than three
times a week). The former became the experimental group and the
latter became the control group. He found that the number of students
in the experimental group outnumbered the number of students in the
control group. He then pared down the size of the experimental group
so that the numbers of students in the experimental and control group
were the same.

Task :
He then sent another questionnaire to them to gather
information from them on their frequency of getting cold in the
following 6 months.
What are the advantages of this kind of experimental
design (Randomised Experimental Design) in scientific
investigation?
4. Please comment on the difficulties Dr Chan may face if he
carries out his research according to your design.

Expensive and time-consuming (for years) to carry out
the experiment;

Must involve a large number of subjects for the
experiment in order to have statistically significant
results;

Must keep other variables constant (fair test) but in
reality it is difficult to control.
P 84
1.
Use a flow chart to illustrate the above experimental design.
2.
The experimental design in (1) is called Prospective
Experimental Design. What are its special features?
3.
What are the advantages of Prospective Experimental
Design over Randomised Experimental Design?
4.
What are the limitations of this kind of experimental design?
5. The experimental design in (1) is called Prospective
Experimental Design. What are the special features of the
Prospective Experimental Design?
Remarks:

Dr. Chan wanted to investigate the link between eating fruits and
immunity from cold. He selected 5000 students randomly from 500
secondary schools in Hong Kong. Then he sent questionnaires to
these students to collect information about their eating habits. He
divided them into 2 groups: those who eat fruits regularly (eating fruits
Activity 2:
Please comment on the difficulties Dr Chan may face if he
carries out his research according to your design.
3.

Please design an experiment to study this research topic
using a control group and an experimental group.
(Use a flow chart / mind map to show your experimental
design).
Activity 1
2.
5. What are the advantages of this kind of
experimental design (Randomised Experimental
Design) in Scientific Investigation?

If a scientist wants to study the effect of a certain
poison on humans, he/she is not allowed to choose
an experimental and control group at random from a
large population.
P 85
The subjects who have been exposed to the suspected cause
(eating fruits regularly in (1)) are selected for the experimental
group while the subjects of the control group who have not
been exposed to the suspected cause (eating fruits less often)
are selected for the control group.
6. What are the advantages of Prospective
Experimental Design over Randomised Experimental
Design?



7. What are the limitations of this kind of
experimental design?

Easier and less expensive to carry out the
study/experiment
May avoid ethical objections
Can pool data from very large group of subjects
thus increasing the accuracy of the experimental
result
The selection process of experimental and control group
usually focuses on one single causal factor, hence it is possible
that other factors will come into play at the very early stage of
the selection process (i.e. the selected subjects having the
suspected cause already affected by other factor(s)).
3. What would the result of Dr. X’s be if acupuncture
treatment can prolong the life span of patients with last
stage liver cancer?

4. What are the pros and cons of
Retrospective Experimental Design?
(i) The advantages of retrospective experimental design are that it is quick
and inexpensive. We only need to analyse the data of past
research/study carefully.
We may look for the percentage difference (life span) between
the experimental and control group. If there is a higher and
significant % of patients who can still live after 1 year in the
experimental group than that of the control group, the study
may support the causal link between acupuncture and
(ii) The disadvantages of retrospective experimental design are as follows:

Can only provide weak evidence for a causal link because there may
be other potential causal factors which are difficult to control in this
kind of experimental design (these potential causal factors other than
the one to be tested for may automatically be built in the experimental
and control group).

Furthermore, retrospective experimental design cannot estimate the
level of difference of the effect being studied.
prolonging of life span of patients with last stage liver cancer.
Reference: Stephen S. Carey (1998)
Retrospective Design.

Another Design involves the collection of data prior to the setting of the
objectives and design of the research. The data can be abstracted
from past studies or researches. This kind of design is called
Retrospective Design.

Retrospective Design: to find the Cause and Effect from past data and
researches.

Key terms:
Suspected Cause (independent variable)
Suspected Effect (dependent variable)
Experimental group: a group of subjects chosen from the population
with the suspected effect (or with improvement after treatment)
Control group: a group of subjects chosen from the population without
the suspected effect (or without improvement after treatment)




Inhalation of air with high oxygen concentration
enhances memory
Exercise:
Activity 3

Task :
P 86
1.
What would the result of Dr. X’s study be if
acupuncture treatment can prolong the life span of
patients with last stage liver cancer?
2.
What are the pros and cons of Retrospective
Experimental Design?
Read the following news and answer the
questions:

Question:
1.
2.
Name the experimental design used by
company X.
Comment on the experimental result and
judge the reliability of the research findings.
P 87
A Japanese electric appliance company X conducted a
research and claimed that inhalation of air with high oxygen
concentration can enhance memory. 80 students were divided
into 2 groups. They were required to take a test on English
vocabulary. Then the experimental group of students inhaled
air of high concentration of oxygen while the control group
breathed ordinary air. Both groups of students were allowed to
have some revision before taking the same vocabulary test
again. It was found that the experimental group could
memorise the vocabulary items 15% more than that of the
control group.
Teachers’ Reference
Activity 1
Lesson 4Experimental Designs
A scientist, Dr. Chan, wants to design an experiment to investigate the following
topic:
Learning Objectives
The effect of taking a nap (a short sleep during the day) on longevity
Students will:
1. Please design an experiment to study this research topic using a control group
and an experimental group.
(Use a flow chart / mind map to show your experimental design).
 have an understanding of the 3 types of causal experiments commonly used in
scientific researches, Randomised Design, Prospective Design and Retrospective
Design;
 be able to identify the type of experimental design being used in the
establishment of causal links;
 be able to know the pros and cons of the 3 types of causal experiments.
Note:
The subjects of this study / experiment will be selected and randomly divided into
two groups prior to administering the suspected causal agent (sleep).
Suggested Lesson Time: 90 min.
P 88
P 89
2. Please comment on the difficulties Dr Chan may face if he carries out his
research according to your design.
Teachers’ Reference
Randomised Experiemental Design
 Expensive and time-consuming (for years) to carry out the experiment;
 Must involve a large number of subjects for the experiment in order to have
statistically significant results
 Must keep other variables constant (fair test) but in reality it is difficult to
control.
Whole population
e.g. Humans/animals/plants
Remarks:
If a scientist wants to study the effect of a certain poison on humans, he/she is
not allowed to choose an experimental and control group at random from a large
population.
Select some
samples at random
as experiment
targets
3. What are the advantages of this kind of experimental design (Randomised
Experimental Design) in scientific investigation?
Randomised Experimental Design can provide strong evidence to support an
hypothesis because other possible causal factors are controlled in the experimental
design.
Control
Group
Experimental Group
(suspected cause)
suspected cause
No Contact with
the suspected
cause
Have contact
with the
suspected cause
Activity 2:
Dr. Chan wanted to investigate the link between eating fruits and immunity from
cold. He selected 5000 students randomly from 500 secondary schools in Hong
Kong. Then he sent questionnaires to these students to collect information about
their eating habits. He divided them into 2 groups: those who eat fruits regularly
(eating fruits every day) and those who seldom eat fruits (eating fruits less than three
times a week). The former became the experimental group and the latter became
the control group. He found that the number of students in the experimental group
outnumbered the number of students in the control group. He then pared down the
size of the experimental group so that the numbers of students in the experimental
and control group were the same.
He then sent another questionnaire to them to gather information from them on their
frequency of getting cold in the following 6 months.
Check
Result
Credit: Stephens S. Carev.
A Beginner’s Guide to
Scientific Method (1998)
P 90
Check
Result
P 91
2. The experimental design in (1) is called Prospective Experimental Design.
What are its special features?
Task
1. Use a flow chart to illustrate the above experimental design
The subjects who have been exposed to the suspected cause (eating fruits regularly
in (1)) are selected for the experimental group while the subjects of the control
group who have not been exposed to the suspected cause (eating fruits less often)
are selected for the control group.
Prospective Experimental Design
Whole Population
e.g. Humans/animals/plants
The others have contact
with the suspected cause.
As targets for Preliminary
Experimental Group
Some members
have no
contact with
the suspected
cause.
3. What are the advantages of Prospective Experimental Design over Randomised
Experimental Design?
Credit: Stephen S. Carev. A
Beginner’s Guide to
Scientific Method (1998)
As targets for Preliminary
Control Group
 Easier and less expensive to carry out the study/experiment;
 May avoid ethical objections;
 Can pool data from very large group of subjects, thus increasing the accuracy of
the experimental result.
4. What are the limitations of this kind of experimental design?
The selection process of experimental and control group usually focuses on one
single causal factor, hence it is possible that other factors will come into play at
the very early stage of the selection process (i.e. the selected subjects having the
suspected cause already affected by other factor(s)).
Adjustment
e.g. Pare down the size of the larger group by randomly excluding subjects from it.
As Final
Experimental Group
As Final
Control Group
Check Result
Check Result
P 92
P 93
Activity 3
Another Design involves the collection of data prior to the setting of the objectives
of the research and the design of the research. The data can be abstracted from past
studies or researches. This kind of design is called Retrospective Design.
Retrospective Experimental Design
Whole population
e.g. Humans/animals/plants
Retrospective Design: to find the Cause and Effect from past data and researches.
Key terms:
Suspected Cause (independent variable)
Suspected Effect (dependent variable)
Experimental group: a group of subjects chosen from the population with the
suspected effect (or with improvement after treatment)
Control group: a group of subjects chosen from the population without the suspected
effect (or without improvement after treatment)
Targets without
Suspected Cause
Targets with
Suspected
Cause
Study the
records of past
Research/Study
that may have
connection with
the Suspected
Cause.
Look to the past
the Experimental
Method/ Treatment
Look to the past
the Experimental
Method/ Treatment
Compare the data to see
whether there are differences of potential causal factors
Provide data/ information to the new Research / Study
Credit: Stephen S. Carev. A
Beginner’s Guide to
Scientific Method (1998)
P 94
P 95
Dr. X wants to use Retrospective Design to carry out a research on the relationship
between acupuncture and the prolonging of life span of patients with last stage liver
cancer. The following flow chart shows his experimental design:
Suspected CauseΚacupuncture
Suspected effect: prolonging of life span of patients with last stage liver cancer
Retrospective Design
Population
Research on the effect of acupuncture on the prolonging of life
span of patients with last stage of liver cancer
Patients with acupuncture treatment
Patients without acupuncture treatment
(suspected cause)
1. What would the result of Dr. X’s study be if acupuncture treatment can prolong the
life span of patients with last stage liver cancer?
We may look for the percentage difference (life span) between the experimental and
control group. If there is a higher and significant percentage of patients who can still live
after 1 year in the experimental group than that of the control group, the study may support
the causal link between acupuncture and prolonging of life span of patients with last stage
liver cancer.
2. What are the pros and cons of Retrospective Experimental Design?
The advantages of retrospective experimental design are that it is quick and inexpensive.
We only need to analyse the data of past research/study carefully.
retrospection
retrospection
Task:
ᡖጊ଺‫ڂ‬
The disadvantages of retrospective experimental design are as follows:
 It can only provide weak evidence for a causal link because there may be other
potential causal factors which are difficult to control in this kind of experimental
design (these potential causal factors other than the one to be tested for may
automatically be built in the experimental and control group).
 Furthermore, retrospective experimental design cannot estimate the level of difference
of the effect being studied.
Reference: Stephen S. Carey (1998)
Experimental group
Control group
% of patients still alive
% of patients still alive
after 1 year
after 1 year
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Exercise:
Students’ Worksheet
Read the following news and answer the questions:
Lesson 4Experimental Designs
Inhalation of air with high oxygen concentration enhances memory
A Japanese electric appliance Company X conducted a research and claimed that
inhalation of air with high oxygen concentration can enhance memory. 80 students
were divided into 2 groups. They were required to take a test on English vocabulary.
Then the experimental group of students inhaled air of high concentration of oxygen
while the control group breathed ordinary air. Both groups of students were allowed
to have some revision before taking the same vocabulary test again. It was found
that the experimental group could memorise the vocabulary items 15% more than
that of the control group.
Activity 1
A scientist, Dr. Chan, wants to design an experiment to investigate the following
topic:
The effect of taking a nap (a short sleep during the day) on longevity
1. Please design an experiment to study this research topic using a control group
and an experimental group.
(Use a flow chart / mind map to show your experimental design).
1. Name the experimental design used by Company X.
2. Comment on the experimental result and judge the reliability of the research
findings.
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2. Please comment on the difficulties Dr Chan may face if he carries out his
research according to your design.
Task:
1. Use a flow chart to illustrate the above experimental design.
3. What are the advantages of this kind of experimental design (Randomised
Experimental Design) in scientific investigation?
Activity 2:
Dr. Chan wanted to investigate the link between eating fruits and immunity from
cold. He selected 5000 students randomly from 500 secondary schools in Hong
Kong. Then he sent questionnaires to these students to collect information about
their eating habits. He divided them into 2 groups: those who eat fruits regularly
(eating fruits every day) and those who seldom eat fruits (eating fruits less than three
times a week). The former became the experimental group and the latter became
the control group. He found that the number of students in the experimental group
outnumbered the number of students in the control group. He then pared down the
size of the experimental group so that the numbers of students in the experimental
and control group were the same.
He then sent another questionnaire to them to collect information from them on their
frequency of getting cold in the following 6 months.
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2. The experimental design in (1) is called Prospective Experimental Design.
What are the special features?
Activity 3
Another Design involves the collection of data prior to the setting of the objectives
and the design of the research. The data can be abstracted from past studies or
researches. This kind of design is called Retrospective Design.
Retrospective Design: to find the Cause and Effect from past data and researches.
3. What are the advantages of Prospective Experimental Design over Randomised
Experimental Design?
Key terms:
Suspected Cause (independent variable)
Suspected Effect (dependent variable)
Experimental group: a group of subjects chosen from the population with the
suspected effect (or with improvement after treatment)
Control group: a group of subjects chosen from the population without the suspected
effect (or without improvement after treatment)
4. What are the limitations of this kind of experimental design?
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Dr. X wants to use Retrospective Design to carry out a research on the relationship
between acupuncture and the prolonging of life span of patients with last stage liver
cancer. The following flow chart shows his experimental design:
Retrospective Experimental Design
Whole population
e.g. Humans/animals/plants
Targets without
Suspected Cause
Targets with
Suspected
Cause
Study the
records of past
Research/Study
that may have
connection with
the Suspected
Cause.
Suspected CauseΚacupuncture
Suspected effect: prolonging of life span of patients with last stage liver cancer
Retrospective Design
Population
Research on the effect of acupuncture on the prolonging of life
span of patients with last stage of liver cancer
Look to the past
the Experimental
Method/ Treatment
Look to the past
the Experimental
Method/ Treatment
retrospection
retrospection
Patients with acupuncture treatment
(suspected cause)
Patients without acupuncture treatment
ᡖጊ଺‫ڂ‬
Compare the data to see
whether there are differences of potential causal factors
Experimental group
Control group
Provide data/ information to the new Research / Study
% of patients still alive
% of patients still alive
after 1 year
after 1 year
Credit: Stephen S. Carev. A
Beginner’s Guide to
Scientific Method (1998)
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Task:
Exercise:
1. What would the result of Dr. X’s study be if acupuncture treatment can prolong
the life span of patients with last stage liver cancer?
Read the following news and answer the questions:
Inhalation of air with high oxygen concentration enhances memory
A Japanese electric appliance Company X conducted a research and claimed that
inhalation of air with high oxygen concentration can enhance memory. 80 students
were divided into 2 groups. They were required to take a test on English vocabulary.
Then the experimental group of students inhaled air of high concentration of oxygen
while the control group breathed ordinary air. Both groups of students were allowed
to have some revision before taking the same vocabulary test again. It was found
that the experimental group could memorise the vocabulary items 15% more than
that of the control group.
2. What are the pros and cons of Retrospective Experimental Design?
1. Name the experimental design used by Company X.
2. Comment on the experimental result and judge the reliability of the research
findings.
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Suggested Learning and Teaching Activities
PowerPoint
Lesson 5 Double-blind Design in Randomized Experimental Design
Level of Students: S.1-S.2
Enhancing Thinking Skills in Science Context
Lesson 5
Learning Objectives
Activity 1
Students will:
 understand the rationale of using Double-blind Design, including the use of
placebo in Randomised Experimental Design;
 be able to evaluate an experimental design using a placebo.
DoubleDouble-blind Design in
Randomised Experimental Design
To study the effect of
coffee on humans’
humans’
concentration power
2
1
Suggested Lesson Time: 90 min.x 2 = 180 min.
Prior knowledge of students:
Students learnt the Randomised Experimental Design in the last lesson. The teacher
may ask the students a few related questions to check their understanding on such
concepts.
Suggested Learning and
Teaching Activities:
Lesson 5 Double-blind
Design in Randomised
Experimental Design
Activity 1
(Randomised Experimental
Design)
Class Discussion of
Experimental Result
Time
allocation
Approx.
180 min.
(2 periods)
90 min.
(1st period)
Materials and apparatus
• 1 packet of coffee A
Remarks
• 1 packet of coffee B
• Enough hot water (at 800C ) for about 45 paper
cups (half full)
The students are divided into groups of 4-5
members to carry out the activities.
(a). The focus of this activity is to let students
experience an experimental design with a placebo
so that they can understand what a double-blind
design is.
(b). The teacher must keep the students from
knowing that coffee B is decaffeinated coffee until
the end of the second counting experiment.
(c). It is better to obtain class data of several
classes for better comparison.
90 min.
(a). The focus of the discussion is on the validity
(2nd period) of the experimental design and students are
required to comment on the validity of method,
ways of data treatment and whether the class
data can provide conclusive evidence to support
the hypothesis that coffee may enhance the
concentration power of humans.
(b). Students are also required to suggest ways to
improve the experimental design.
(c). Students should know the rationale of using
double-blind design in scientific researches.
• 1 bottle of coffee creamer
Hypothesis:
• 50 spoons
• 1 bag of red rice (net weight: 1.5 kg)
Coffee may enhance the
concentration power of
humans.
• 1 bag of white rice (net weight: 2 kg)
• 45 Petri dishes
• 45 Heat resistant paper cups
3
4
Procedure:
a)
The class is randomly divided into three groups(A, B and C), each
each
of which consisting of roughly the same number of students.
Group A: coffee A + coffee creamer [Drink A]
b)
Each of you will be given a Petri dish containing wellwell-mixed red and
white rice in the ratio 2:1 (approx.).
c)
Each of you is required to pick out the red rice from the white rice by
hand at constant speed.
d)
Each of you is required to record down the number of red rice
picked up in five minutes.
e)
Record down the total no. of red rice picked up by the different
groups of students in five minutes.
f)
Then each group will be given drinks according to their group
number immediately after step (e):
(e):
(3 spoonful of coffee A + 2 spoonful of coffee creamer
+ half cup of hot water (800C) + stirring)
Group B: coffee B + coffee creamer [Drink B]
(3 spoonful of coffee B + 2 spoonful of coffee creamer
+ half cup of hot water (800C) + stirring)
Group C: water + coffee creamer [Drink C]
(2 spoonful of coffee creamer
+ half cup of hot water (800C) + stirring)
6
5
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Procedure:
Result
Group A (Taken Drink A)
(g) Thirty minutes after taking the drink each of you will be
required to repeat steps (b), (c), (d) and (e).
First counting
experiment before
taking the drink:
No. of red rice picked
up from a mixture of
red and white rice in
5 minutes
Student
8
7
1
2
3
4
5
6
13
Result
Group B (Taken Drink B)
Student
9
10
First counting
experiment before
taking the drink:
No. of red rice
picked up from a
mixture of red and
white rice in 5
minutes
Student
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Second counting
experiment after
taking the drink:
No. of red rice picked
up from a mixture of
red and white rice in
5 minutes
16
Task:
1. Why was the experiment repeated? (i.e. why do we
need to do the first counting experiment and then do
the second experiment? )
12
First counting
experiment before
taking the drink:
No. of red rice picked
up from a mixture of
red and white rice in
5 minutes
1
2
3
4
5
6
Task:
11
14
Result
Group C (Taken Drink C)
Second counting
experiment after
taking the drink:
No. of red rice
picked up from a
mixture of red and
white rice in 5
minutes
1
2
3
4
5
6
Second counting
experiment after
taking the drink:
No. of red rice picked
up from a mixture of
red and white rice in
5 minutes
2. Why was the second experiment carried
out 30 minutes after taking the drink?
17
18
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Task:
Discussion
of Experimental Results
Task:
4.Compare the results of group A, B and C obtained from (3).
Does the result obtained support the hypothesis that coffee
may enhance the concentration power of humans? Please
explain your answers.
3. Pool the group and class data after the
experiment. You may need to do some
calculation in order to obtain more conclusive
result. Show the details of your treatment of
the class data.
Average of Percentage Increase of Mean
(Class 2A and 2C)
a) Standard deviation indicates how spread out a set of data
is, that is, whether the data are relatively close together
and clustered around the mean or spread out.
b) Referring to the standard deviation difference of Class 2A,
2B and 2C the difference in standard deviation of Class 2B
is the greatest for Drink A and Drink B, which makes the
data collected in class 2B not so trustworthy. However, the
differences in standard deviation of class 2A and 2C are
reasonable. Hence, the result of Class 2B was discarded
but the results of Class 2A and 2C are combined to see
whether there is any significant evidence for drawing a
conclusion.
Class data obtained from
2A, 2B, 2C
Compare the results and try to draw a conclusion.
Control
Drink A
Drink B
16.6%
22%
39.3%
If set 0,
(slightly greater than
5.4
that of the Control)
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22%
39.3%
If set 0,
5.4
22.7
Drink B is decaffeinated coffee
•
•
It contains nearly no caffeine
(only 0.1% caffeine).
It was supposed to be used as a placebo.
22.7
27
28
A DoubleDouble-blind Study
A DoubleDouble-blind Study
23
16.6%
(much greater than that
of the Control and
of the “Drink A” group)
22
21
Drink B
26
Average of Percentage Increase of Mean
(Class 2A and 2C)
The following data of the above experiment was
obtained from 3 classes (105 Secondary 2
students) of a school.
Drink A
25
20
19
Control
•
A double-blind study, relatively easy to achieve in drug
studies, belongs to the category of Randomised
Experimental Design. Two similar groups of people
(experimental and control) act as targets of the study. The
experimental group is given an actual treatment (e.g. an
investigational drug) while the control group is given a
placebo (may be a sugar pill), which has identical
appearance (e.g. colour, taste, size) as the investigational
drug.
•
A placebo is a preparation which is pharmacologically inert
but which may have a medical effect solely on the power of
suggestion, a response known as the placebo effect.
•
Furthermore, people are randomly assigned to the
control or experimental group and given random
numbers by a study co-ordinator, who also encodes the
investigative drug and the placebo with matching
random numbers. Neither the experimental subjects
(both the control and experimental group) nor the
researchers monitoring the outcome of the study know
who is receiving which treatment (the investigative drug
or the placebo), until the study is over and the random
code is broken. Such an arrangement would prevent the
subjects from biasing the result by knowing which group
they are in.
30
29
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•
•
Teachers’ Reference
Average of Percentage Increase of Mean (Class 2A and 2C)
A DoubleDouble-blind Study
If later it is found that results from the experimental
group is better than that of the control group, the
treatment or the drug given to the experimental group
is assumed to have an effect.
Control
Drink A
Drink B
16.6%
22%
39.3%
If set 0,
5.4
(slightly greater than
that of the Control)
22.7
(much greater than
that of the Control and
of the “Drink A” group)
Drank coffee during
the experiment
Drank decaffeinated
(only 0.1% caffeine)
coffee during the
experiment
Finally, the same experiment (study) need to be
replicated on a large group of subjects in order that
more significant conclusion can be drawn about the
effect of the investigative drug.
Lesson 5
Learning Objectives
Implication: The result obtained from the Control, Drink A Group and
Drink B Group is not conclusive ((a) The result of Drink A group is only
slightly greater than that of the Control (not a significant difference); (b)
The placebo effect of Drink B Group should not be so great when
compared with Drink A Group and the Control).
31
Double-blind design in randomised experimental design
32
Students will:
 understand the rationale of using Double-blind Design, including the use of
placebo in Randomised Experimental Design;
 be able to evaluate an experimental design using a placebo.
Focus ideas:
The double-blinded method is commonly used in scientific researches because it can
prevent research findings from being influenced by the placebo effect and the bias of
the scientists. Blinded research is an important tool in many research domains such
as medicine and forensic science.
Discussion Questions
1)
Is the experimental design a double-blind design?
Explain your answer.
2)
Is the experimental design a valid design? Explain your
answer.
3)
If the experimental design is not a valid one, suggest
ways to improve the experimental design?
1) Is the experimental design a double-blind design? Explain
your answer.
The experimental design is a single-blind, not a double-blind
because the teacher knows the details of the drink and which
group of students would take which drink.
33
34
3) If the experimental design is not a valid one, suggest ways to
improve the experimental design?
2) Is the experimental design a valid design? Explain your answer.
Ways to improve the experimental design may be as follows:
Judging from the Percentage Increase (Mean) of Drink A, B and
the Control of Class 2A and 2C the experimental design is not a
valid design. Possible reasons may be as follows:
•
•
•
•
•
Key terms related to double-blinded method:
 Experimental group
 Control group (taking a placebo)
 Randomisation
 Replication
Suggested answers:
•
•
The sample size is too small;
The suggested method is not a valid method to measure the
concentration power of humans;
Some students may drink coffee during lunch or breakfast
and hence may interfere with the experimental result
Some students are more skillful at doing such task requiring
good motor skills;
The effect of coffee is not significant because the “dose” is
not enough.
•
•
•
•
35
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To increase the sample size (invite more classes to do the
experiment);
To use another method to measure the concentration power of the
experimental subjects, e.g. Use photographic memory method
(eidetic imagery, in which a person memorises details of a complex
scene at a glance) to measure the concentration power of the
experimental subjects
Scattered numerals would appear for up to two-thirds of a second in
the computer screen and were then masked by white squares.
Each student is required to write down the numerals on a worksheet
according to their previous location within a fifth of a second.
The same procedure with 10 different sets of numerals repeats for
10 times and the students would check the answers after the activity.
The percent accuracy of each student is counted and then the sum,
the mean, percentage increase, standard deviation are collected for
comparison among the three groups of students drinking the control, 36
drink A and drink B.as before.
A double-blind study, which is relatively easy to achieve in drug studies, belongs to
the category of Randomised Experimental Design. Two similar groups of people
(experimental and control) are studied. The experimental group is given an actual
treatment (e.g. an investigational drug) while the control group is given a placebo
(may be a sugar pill), which has identical appearance (e.g. colour, taste, size) as the
investigational drug. A placebo is a preparation, which is pharmacologically inert,
may have a medical effect solely on the power of suggestion and such a response is
known as the placebo effect.
People are randomly assigned to the control or experimental group and given random
numbers by a study co-ordinator, who also encodes the investigative drug and the
placebo with matching random numbers. Neither the experiment subjects (both
the control and experimental group) nor the researchers monitoring the outcome
of the study know the treatment both groups are receiving (the investigative drug
or the placebo), until the study is over and the random code is broken. Such an
arrangement would prevent the subjects from biasing the result by knowing which
group they are in.
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If later it is found that the results from the experimental group is better than that
of the control group, the treatment or the drug given to the experimental group
is assumed to have an effect. Finally, the same experiment (study) needs to be
replicated on a large group of subjects so that a more significant conclusion can be
drawn about the effect of the investigative drug.
Suggested Lesson Time: 90 min.x 2 = 180 min.
Activity 1
Objective: To study the effect of coffee on humans’ concentration power.
Hypothesis: Coffee may enhance the concentration power of humans.
Materials and apparatuses
 1 packet of coffee (coffee A)
 1 packet of decaffeinated coffee (coffee B)
 Enough hot water (at 800C ) for about 45 paper cups (half full)
 1 bottle of coffee creamer
 50 spoons
 1 bag of red rice (net weight: 1.5 kg)
 1 bag of white rice (net weight: 2 kg)
 45 Petri dishes
 45 Heat resistant paper cups
 Teachers should note that some students may be sensitive or allergic to coffee.
Such students are not advised to join the coffee drinking group and they may
join the control group instead.
Procedure:
(a) The class is randomly divided into three groups (A, B and C), each of which
consisting of roughly the same number of students.
(b) Each of you will be given a Petri dish containing well-mixed red and white rice
in the ratio 2:1 (approx.).
(c) Each of you is required to pick out the red rice from the white rice by hand at
constant speed.
(d) Each of you is required to record down the number of red rice picked up in five
minutes.
(e) Record down the total no. of red rice picked up by the different groups of
students in five minutes.
(f) Then each group will be given drinks according to their group number
immediately after step (e):
Group A: coffee A + coffee creamer [Drink A]
(3 spoonful of coffee A + 2 spoonful of coffee creamer
+ half cup of hot water (80℃) + stirring)
Group B: coffee B + coffee creamer [Drink B]
(3 spoonful of coffee B + 2 spoonful of coffee creamer
+ half cup of hot water (80℃) + stirring)
Group C: water + coffee creamer [Drink C]
(2 spoonful of coffee creamer + half cup of hot water (80℃) + stirring)
Remarks for preparation of drinks:
 The white rice and the red rice would be mixed thoroughly according to the
ratio 2:1
 Each Petri dish is filled 1/3 full with the mixture of white and red rice.
 Coffee A is blended soluble coffee containing no glucose syrups.
 Coffee creamer contains glucose syrups to add flavour to the coffee.
(g). Thirty minutes after taking the drink each of you will be required to repeat steps
(b), (c), (d) and (e).
Remarks: If the students are required to prepare the drinks themselves, the teacher
needs to show the students what a full spoonful of coffee is so as to keep the amount
of coffee being added to each paper cup the same for group A and B.
Safety Precautions:
 It is better to carry out the drinking experiments in a clean classroom and
students should wash their hands before doing the drinking experiment.
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Result
Group B (Taken Drink B)
Student
Group A (Taken Drink A)
Student
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Sum
Mean
Sum
Mean
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Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
Task:
Group C (Taken Drink C)
Student
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1. Why was the experiment repeated? (i.e. why do we need do the first counting
experiment and then do the second experiment? )
To minimse the practice effect.
2. Why was the second experiment carried out 30 minutes after taking the drink?
It generally takes 15 or more minutes for caffeine to take effect.
3. Pool the group and class data after the experiment. You may need to do some
calculation in order to obtain a more conclusive result. Show the details of your
treatment of the class data.
Each group of students may calculate
 Mean, Standard Deviation of the counts before and after the experiment
 % increase of the Mean of each group
 the difference between the Standard Deviation before and after the experiment
of each group
4. Compare the results of group A, B and C obtained from (3). Does the result
obtained support the hypothesis that coffee may enhance the concentration
power of humans? Please explain your answers.
Sum
Mean
Teacher’s note:
If coffee (active ingredient is caffeine) may enhance the concentration power of
humans and the experimental design of this activity could really show the effect,
there should be valid evidence obtained from the experimental result. If it is so,
then
 the group of students taken coffee (group A) would perform better than the
control group (group C) and group B (taken the placebo)
 students taken the placebo, decaffeinated coffee B (may contain 0.1% caffeine)
may perform better than the Control Group showing that a placebo may have an
effect based solely on the power of suggestion.
Students are required to evaluate whether there is a valid evidence to support
the hypothesis by examining the design of the experiment, the collected data
(measurement), the way the results are presented, the interpretation of the results.
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Finally, the students should also consider the reliability of the experimental result
before drawing the conclusion.
If the experimental design is valid,
 the group taken coffee (with caffeine) is expected to pick out most red rice due
to higher concentration power;
 the group taken decaffeinated coffee (may contain 0.1% caffeine) may also
perform better than the control group (though may not be better than the group
taken coffee) due to the placebo effect.
 DON’T tell group B students they are drinking decaffeinated coffee in the
course of the experiment. Tell them they are drinking another brand of coffee.
 The purpose of adding coffee creamer is to make it easier for students to drink
the coffee.
 Some research has shown that drinking coffee will take about 15 minutes to
achieve 75% of its maximum effects and one hour to reach its maximum effect.
In this experiment the students are required to do the second counting
experiment 30 minutes after taking the drink.
Students’ Worksheet
Lesson 5 Double-blind design in Randomised Experimental Design
Activity 1
Objective: To study the effect of coffee on humans’ concentration power.
Hypothesis: Coffee may enhance the concentration power of humans.
Materials and Apparatuses
 1 packet of coffee A
 1 packet of coffee B
 Enough hot water (at 80℃ ) for about 45 paper cups (half full)
 1 bottle of coffee creamer
 50 spoons
 1 bag of red rice (net weight: 1.5 kg)
 1 bag of white rice (net weight: 2 kg)
 45 Petri dishes
 45 Heat resistant paper cups
Remarks for preparation of drinks:
 The white rice and the red rice would be mixed thoroughly according to the
ratio 2:1
 Each Petri dish is filled 1/3 full with the mixture of white and red rice.
Procedures:
(a) The class is divided into three groups (A, B and C), each of which consisting
of roughly the same number of students.
(b) Each of you will be given a Petri dish containing well-mixed red and white
rice with the ratio 2:1 (approx.).
(c) Each of you is required to pick out the red rice from the white rice by hand at
constant speed.
(d) Each of you is required to record down the number of red rice picked up in five
minutes.
(e) Record down the total no. of red rice picked up by the different groups of
students in five minutes.
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(f) Then each group will be given drinks according to their group number
immediately after step (e):
Group A: coffee A + coffee creamer [Drink A]
(3 spoonful of coffee A + 2 spoonful of coffee creamer
+ half cup of hot water (80℃) + stirring)
Group B: coffee B + coffee creamer [Drink B]
(3 spoonful of coffee B + 2 spoonful of coffee creamer
+ half cup of hot water (80℃) + stirring)
Group C: water + coffee creamer [Drink C]
(2 spoonful of coffee creamer + half cup of hot water (80℃) + stirring)
(g). Thirty minutes after taking the drink each of you will be required to repeat steps
(b), (c), (d) and (e).
Result
Group A (Taken Drink A)
Student
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Sum
Mean
P 124
P 125
Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
Group C (Taken Drink C)
Group B (Taken Drink B)
Student
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
Student
First counting experiment
before taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Sum
Mean
Sum
Mean
P 126
P 127
Second counting experiment
after taking the drink:
No. of red rice picked up from
a mixture of red and white
rice in 5 minutes
Task:
1. Why was the experiment repeated? (i.e. why do we need do the first counting
experiment and then do the second experiment? )
4. Compare the results of Group A, B and C obtained from (3). Does the result
obtained support the hypothesis that coffee may enhance the concentration
power of humans? Please explain your answer.
2. Why was the second experiment carried out immediately after taking the drink?
3. Pool the group and class data after the experiment. You may need to do some
calculation in order to obtain more conclusive result. Show the details of your
treatment of the class data.
P 128
P 129
Suggested Learning and Teaching Activities
Activity 3
Redesign the bridge
15 min.
The focus of Activity 3 is to let students
consolidate what they learn from engineering
principles, which in turn enhancing their
critical thinking skills.
Activity 4
Bridge Building Contest
35 min.
The focus of Activity 4 is to encourage
students to actively participate in the lesson
and let them apply critical thinking skills
learned in the Engineering Process.
Activity 5
Professional’s judgment
10 min.
The focus on doing Activity 5 is to broaden
students’ horizon through the expert’s
comment on their bridge designs-students
need to answer critical questions from the
expert and defend their design.
Lesson 6 - Critical Thinking in Engineering Process
Level of Students: S.1-S.2
Suggested Lesson Time: 90 min
Learning Objectives:
Students will:
 understand the steps suggested by Isidro-Cloudas and Cassis, Glenn in
engineering process;
 be able to enhance their critical thinking skills through the bridge building
process.
Materials and Apparatus for each group:
80 drinking straws, 1 sticky tape, 10 paper clips, 1 pair of scissors, 1 roll of strings,
some A4 papers.
Prior knowledge of students:
The teacher can ask a few simple questions about the science related to bridges to
have a general view on students’ knowledge on bridge design.
Suggested Learning and
Teaching Activities:
Lesson 6 (approx. 90
min.)
Introduction to the
different types of bridges
Time allocation
Remarks
10 min.
The focus is to let students know the different
types of bridges, including beam, arch, truss,
cable-stayed and suspension bridges prior to
further activities.
Activity 1
Draft a design
10 min.
 The focus of Activity 1 is to motivate students
to think about the steps to solve the problem.
Activity 2
Introduction to
engineering process
suggested by IsidroCloudas and Cassis,
Glenn in engineering
process
10 min.
The focus is to let students learn the steps
involved in the Engineering Process.
P 130
P 131
PowerPoint
What factor(s) should you consider when you build an
arch bridge?
Enhancing Thinking Skills in Science Context
Lesson 6
Introduction to the different types of bridges
beam
bridge
bridge
arch bridge
Critical Thinking
in Engineering Process
suspension
Why are there different types of bridges?

Beam Bridge
The major difference between the three types of
bridges is the distance that they can cover in a
single span. Span is the difference between two
supports. Each of the different types of bridges
holds weight in different ways.

What happens to the bridge when a load is put on
the bridge?

A beam bridge is basically a rigid horizontal
structure that rest on two supports, one located at
each end of the bridge as shown in Figure (a). A
simple beam bridge is flat across and supported by
two ends.
What factor(s) should you consider when you build a
beam bridge?
When the load pushes down on the beam the
top edge is pushed together or compressed,
while the bottom of the beam is stretched or
is under tension.
The beam must be strong enough so that it can
support its own weight together with the added
weight of the traffic crossing it.

What happens to the bridge when a load is put on
the bridge?
Arch Bridge



An arch bridge is composed of a
curved structure with abutments on
each end.
The weight of the load is carried outward along the
curve of the arch to the abutments at each end of
the arch. The abutments also keep the end of the
bridge from spreading outward.
Suspension Bridge
The arch bridge is always under compression
because the weight of the deck is pushed outward
along the curve of the arch towards the abutments.
The rise in the form of the curved arch causes the
vertical load to have a horizontal thrust.

What happens to the bridge when a load is
put on the bridge?

The suspension bridge literally suspends the
roadbed from huge cables, which extends from one
end of the bridge to the other. The cables are
attached to two tall towers and are secured at each
end by anchorages.
What factor(s) should you consider when you build a
suspension bridge?
The cable carries the weight on a suspended bridge
to the anchorages that are imbedded in solid rock
or massive concrete blocks. The cables are spread
over a large area in order to evenly distribute the
load inside the anchorages to prevent the cables
from breaking free.

The anchorages help to stabilise the bridge.
Therefore, the tower must be embedded to the
earth firmly. In such a way, the cables transfer the
forces to the towers which carry the forces directly
into the earth where they are firmly imbedded.
Scenario

Activity 1
The class is divided into groups of 4 or 5. You are
required to design and build a bridge made of
drinking straws. The bridge will cross a gap of
50cm. The width of the bridge must not be less
than 20cm. The total mass of the bridge must not
exceed 50 g. The strength of the bridges would be
tested by hanging loads from the middle of the
bridges.
Draft a design
Activity 1

Activity 2
Now, you have 10 minutes to discuss with your
group members to design the bridge. Draft the
steps you come across. Also, sketch a picture of
the bridge you intend to build.
Introduction to the steps suggested by
Isidro-Cloudas and Cassis, Glenn in
engineering process
P 132
P 133
Activity 2
Activity 2
The steps involved in Engineering Process are
written on 6 cardboards. You are required to design
a bridge. Arrange the cardboards in correct order.
Try to answer the following questions.


Activity 2

Identify the Problem
Determine the Constraints
Brainstorm the preliminary design and
choose the best design
Analysis of Design
Design Refinement
Implementation Plan






Activity 2

Identify the Problem




Design Refinement


Answer

Once both the problem(s) or task have been
determined and the constraints have been identified,
the group needs to think of as many ways as possible
to solve the problem. Even though all of the ideas
may not be good ones, they may inspire another idea
that may lead to a solution to the problem(s).
Once all reasonable ideas are listed and the sketches
are drawn, the group should choose the best two or
three ideas for further development. The rough
sketches should be converted to scaled or measured
drawings.
Analysis of Design

P 134
The designs are studied based on their merit
in relationship to strength, cost, market
appeal, and manufacturability. A decision
should be made at this point on which design
to use or rather to begin a new design.
Answer

Each design team should attempt to rectify
the problems by making improvements in the
design.
Implementation Plan

Once the final design has been approved, it
must be translated from an idea on paper to
the real thing.
Activity 3
Activity 3

Redesign the bridge

Materials provided
80 drinking straws, 1 sticky tape, 10
paper clips, 1 pair of scissors, 1 roll of
strings, some A4 papers.
Points can be earned by the following rules.
 The drawing is neat and legible.
 The three spatial views are labelled.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge
supports is at least 10 cm apart.
Activity 3
Activity 3

According to steps of Engineering
Process, draw a completed design of
the bridge you intend to build. THREE
spatial views of the bridge should be
included. You may consider the
materials provided and the following
rubrics to draw the diagram:
Activity 3
Activity 3
Constraints are the limitations that must be
considered before you begin designing your
bridge.
Activity 2
Brainstorm the preliminary design and choose
the best design

Answer

Determine the Constraints

Answer

Answer

Before you start, the problem or task that is
going to be undertaken must be known.
Activity 2

Question:
What is/are the task(s) performed in
each step of Engineering Process?
Activity 2
Answer


Activity 2
Activity 2
Answer:

Question:
What is the sequence of Engineering
Process to design the bridge?
Activity 2
Question:
Compare the steps you drafted with
the Engineering Process. Discuss
among yourselves which steps you
need to reconsider.

P 135
Question:
What are the constraints when you
build a bridge?
Teachers’ Reference
Activity 3

Activity 4
Answers:
Weight, length and width of the bridge,
materials and other requirements of
the bridge itself.
Bridge Building Contest
Lesson 6 - Critical Thinking in Engineering Process
Learning Objectives
Students will:
 understand the steps suggested by Isidro-Cloudas and Cassis, Glenn in
engineering process;
 be able to enhance their critical thinking skills through the bridge building
process.
Activity 4

Activity 4
Build a bridge according to your
completed design. You may change
your design if there is a serious
problem in your design. You may refer
to the rubrics to build the bridge. The
strength of the bridges would be tested
by hanging loads from the middle of
the bridges until it begins to buckle.

At the end of this activity, you are
going to evaluate the designs of
different groups and choose

a.

b.
the most cost-effective design
(materials used vs strength)
the strongest bridge design
Activity 4
Activity 5
Points can be earned by the following rules.
 The team adhered to the design.
 The model is neatly done.
 The model is built with materials supplied.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge supports is
at least 10 cm apart.
Professional’s judgment
Suggested Lesson Time: 90 minutes
Introduction to the different types of bridges
There are three different types of bridges, beam bridge, suspension bridge and arch
bridge.
Q: Why are there different types of bridges?
A: The major difference between the three types of bridges is the distance that they
can cover in a single span. Span is the difference between two supports. Each of the
different types of bridges holds weight in different ways.
Major types of bridges
 Beam Bridge
A beam bridge is basically a rigid horizontal structure that rests on two supports, one
located at each end of the bridge as shown below. A simple beam bridge is flat and
supported at two ends.
Activity 5

An expert or professional is invited to
give you comments so that you know
which aspects of the bridge design
need improvements.
P 136
P 137
Q: What happens to the bridge when a load is put on the bridge?
A: When the load pushes down on the beam, the top edge is pushed together or compressed, while
the bottom of the beam is stretched or is under tension as shown below.
Q: What factor(s) should you consider when you build an arch bridge?
A: The arch bridge is always under compression because the weight of the deck is
pushed outward along the curve of the arch towards the abutments. The rise in the
form of the curved arch causes the vertical load to have a horizontal thrust.
 Suspension Bridge
The suspended bridge literally suspends the roadbed from huge cables, which extend
from one end of the bridge to the other. The cables are attached to two tall towers
and are secured at each end by anchorages.
Q: What factor(s) should you consider when you build a beam bridge?
A: The beam must be strong enough so that it can support its own weight and the added weight of
the traffic crossing it.
 Arch Bridge
An arch bridge is composed of a curved structure with abutments on each end.
Q: What happens to the bridge when a load is put on the bridge?
A: The cable carries the weight on a suspended bridge to the anchorages that are
imbedded in solid rock or massive concrete blocks. The cables are spread over a
large area in order to evenly distribute the load inside the anchorages to prevent the
cables from breaking free.
Q: What factor(s) should you consider when you build a suspension bridge?
A: The anchorages help to stabilise the bridge. Therefore, the tower must be embedded
to the earth firmly. In such a way, the cables transfer the forces to the towers which
carry the forces directly into the earth where they are firmly imbedded.
Scenario
Q: What happens to the bridge when a load is put on the bridge?
A: The weight of the load is carried outward along the curve of the arch towards the abutments at
each end of the arch. The abutments keep the end of the bridge from spreading outward.
The class is divided into groups of 4 or 5. You are required to design and build a
bridge by drinking straws. The bridge will cross a gap of 50 cm. The width of the
bridge must not less than 20 cm. The total mass of the bridge must not exceed 50
g. The strength of the bridges would be tested by hanging loads from the middle of
the bridges.
Activity 1 Draft a design
Now, you have 10 minutes to discuss with your group members on how to design
the bridge. Draft the steps you come across. Also, sketch a picture of the bridge you
intend to build.
P 138
P 139
Activity 2 Introduction to the steps suggested by Isidro-Cloudas and Cassis, Glenn
in engineering process
The Engineering Process for the steps in designing a bridge is written on 6 cardboards.
Arrange the cardboards in correct order. Try to answer the following questions.
Q: What is the sequence of Engineering Process to design the bridge?
A:
1. Identify the Problem
2. Determine the Constraints
3. Brainstorm the preliminary design and choose the best design
4. Analysis of Design
5. Design Refinement
6. Implementation Plan
Q: What is/are the task(s) performed in each step of Engineering Process?
A:
1. Identify the Problem(s)
Before you start, the problem(s) or task(s) that are going to be undertaken must be
known.
2. Determine the Constraints
Constraints are the limitations that must be considered before you begin designing
your bridge.
3. Brainstorm the preliminary design and choose the best design
 Once both the problem or task has been determined and the constraints have been
identified, each group needs to think as many ways as possible to solve the problem.
Even though all of the ideas may not be the good ones, they may inspire another
ideas that may lead to a solution to the problem.
 Once all reasonable ideas are listed and the sketches are drawn, each group should
choose the best two or three ideas for further development. The rough sketches
should be converted to the scaled or measured drawings.
5. Design Refinement
Each design team should attempt to rectify the problems by making improvements
in the design.
6. Implementation Plan
Once the final design has been approved, it must be translated from an idea on paper
to the real thing.
Remark: The original plan may be changed if there is a serious problem.
Activity 3 Redesign the bridge
According to steps of Engineering Process, draw a completed design of the bridge
you intend to build. THREE spatial views of the bridge should be included. You may
consider the materials provided and the following rubrics to draw the diagram.
Materials provided
80 drinking straws, 1 sticky tape, 10 paper clips, 1 pair of scissors, 1 roll of strings,
some A4 papers.
Points can be earned by the following rules.
 The drawing is neat and legible.
 The three spatial views are labled.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge supports is at least 10 cm apart.
Q: Compare the steps you drafted with the Engineering Process. Discuss with
what steps you need to consider again?
Q: What are the constraints when you build a bridge?
A: Weight, Length of the bridge, materials, requirements of the bridge itself such as
the width of the bridge
4. Analysis of Design
The designs are studied based on their merit in relationship to strength, cost, market
appeal, and manufacturability. A decision should be made at this point on which
design to use or rather to begin a new design.
P 140
P 141
Activity 4 Bridge Building Contest
Students’ Worksheet
Build a bridge according to your completed design, you may change your design
if there is a serious problem in your design. You may refer to the rubrics to build
the bridge. The strength of the bridges would be tested by hanging loads from the
middle of the bridges until it begins to buckle.
Lesson 6 - Critical Thinking in Engineering Process
1. There are three different types of bridges, name them. Why are there different
types of bridges?
At the end of this activity, you are going to evaluate the designs of different groups
and choose
a. the most cost-effective design (materials used vs strength)
b. the strongest bridge design
Points can be earned by the following rules.
 The team adhered to the design.
 The model is neatly done.
 The model is built with materials supplied.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge supports is at least 10 cm apart.
2. What happens to the bridge when a load is put on each type of bridge?
Activity 5 Professional’s judgment
An expert or professional is invited to give you comments so that you know which
aspects need improvements or how to improve your design.
Reference reading for building bridge
http://www.yale.edu/ynhti/curriculum/units/2001/5/01.05.04.x.html#d
Activity 1
The class is divided into groups of 4 or 5. You are required to design and build a
bridge by drinking straws. The bridge will cross a gap of 50 cm. The width of the
bridge must not less than 20 cm. The total mass of the bridge must not exceed 50 g.
The strength of the bridges would be tested by hanging loads from the middle of the
bridges.
Now, you have 10 minutes to discuss with your group members on how to design
the bridge. Draft the steps you come across. Also, sketch a picture of the bridge you
intend to build.
P 142
P 143
Activity 2
Activity 4
The Engineering Process for the steps in designing a bridge is written on 6 cardboards.
Arrange the cardboards in correct order. Try to answer the following questions.
Materials :
80 drinking straws, 1 sticky tape, 10 paper clips, 1 pair of scissors, 1 roll of strings,
some A4 papers.
What is the sequence of Engineering Process in designing a bridge? What is/are the
task(s) performed in each step of Engineering Process?
Build a bridge according to your completed design. You may change your design
if there is a serious problem in your design. You may refer to the rubrics to build
the bridge. The strength of the bridges would be tested by hanging loads from the
middle of the bridges until it begins to buckle.
At the end of this activity, you are going to evaluate the designs of different groups
and choose
a. the most cost-effective design (materials used vs strength)
b. the strongest bridge design
Points can be earned by the following rules for the Model
 The team adhered to the design.
 The model is neatly done.
 The model is built with materials supplied.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge supports is at least 10 cm apart.
Activity 3
According to the steps of Engineering Process, draw a completed design of the
bridge you intend to build. THREE spatial views of the bridge should be included.
You may consider the materials provided and the rubrics to draw the diagram:
Materials provided in building bridge
80 drinking straws, 1 sticky tape, 10 paper clips, 1 pair of scissors, 1 roll of strings,
some A4 papers.
Points can be earned by the following rules for the Bridge Design :
 The drawing is neat and legible.
 The three views are labelled.
 The bridge span is at least 30 cm long.
 The roadbed is at least 5 cm wide.
 The distance between the bridge supports is at least 10 cm apart.
P 144
P 145
Suggested Learning and Teaching Activities
PowerPoint
Lesson 7 - Arguments in Science
Level of Students: S.1-S.2
Suggested Lesson Time: 90 min
Enhancing Thinking Skills
in Science Context
Lesson 7
Learning Objectives:
Activity 1

Arguments in Science
Students will be able to:

understand the components of an argument;

identify claims and evidences of arguments;

decide which arguments has more supportive evidence.
Use the resource listed below to search
evidence for and against ‘genetically modified
(GM) food being safe for humans to eat’.
Take your side according to the evidence
drawn. You will be required to present your
argument to your group.
http://www.beep.ac.uk/content/392.0.html
Prior knowledge of students:
Students learnt the basics of scientific investigation in S.1. The teacher can ask a
few simple questions on arguments in science to have a general view on students’
knowledge on the topic.
Suggested Learning
and Teaching
Activities:
Lesson 7
(approx. 90 min.)
Activity 1
Time
Remarks
allocation
20 min
The focus of Activity 1 is to give an
opportunity for students to construct the
arguments.
Activity 2
10 min
The focus of Activity 2 is to improve
students’ skills in relating evidence and
claim.
Activity 3
60 min
The focus of Activity 3 is to improve
students’ skills in deciding which argument
has more supportive evidence.
Activity 1


Activity 1
Question:
What kind of evidence can be used to support
an argument?
Answer:
Data, survey result, research result, facts,
truth, legal documents, professional
knowledge, common sense recognised by
public.


Activity 1

Question:
Does all evidence support one point of view
only?
Answer:
No. Evidence can be used to support any
related arguments.
Activity 1
Question:
Are your arguments easily overthrown by
your group members?

Answer:
It is because the problems in arguments are not in the
evidence, but always in the proof of the evidence.
In order to have a strong argument, the following
points should be considered.



P 146
P 147
a.
b.
c.
Is there enough evidence to support you?
Is the evidence credible or convincing?
Is the evidence valid or correct?
Teachers’ Reference
Activity 1


Activity 2
Question:
What are the components of an argument?

Answers:
ARGUMENT = CLAIM + EVIDENCE



Claim is a thesis in an argument.
Argument or claim should be supported by
evidence.
You may work in pairs to identify each of the
following claims in worksheet A as in favour
or against GM crops. Label them as for or
against respectively.
In addition, you should consider each of the
following claims from the perspectives
concerning with human health, environment
or economics (label them as HH, ENT, ECON
respectively).
Lesson 7 - Arguments in Science
Learning Objectives
Students will be able to:
 understand the components of an argument;
 identify claims and evidences of arguments;
 decide which arguments has more supportive evidence.
Suggested Lesson Time: 90 minutes
Activity 1
Activity 3
Activity 2

Cut up worksheet A and B. Select evidence
from worksheet B to support the relevant
claim. There will be more than one piece of
evidence for most of the arguments.

Scenario
The class would be divided into 3 groups - supporters and
opponents of GM crops as well as the adjudicators. The
group in support of GM crops will present their claims and
the corresponding evidences first. Then the opposition group
may challenge the claims and the evidences. The supporter
group can rebut. Then the whole process will go through
once more with the opposition group. The adjudicators
would comment on the performance of the supporter group
and the opposition group, and finally decide whether they
would be supporters or opponents of GM crops.
Use the resource listed below to search evidence for and against ‘genetically modified
(GM) foods being safe for humans to eat’. Take your side according to the evidence
drawn. You will be required to present your argument to your group.
http://www.beep.ac.uk/content/392.0.html
Q: What kind of evidence can be used to support an argument?
A: Data, survey result, research result, facts, truth, legal documents, professional
knowledge, common sense recognised by public
Q: Does all evidence support one point of view only?
A: No, evidence can be used to support any related arguments.
Q: Are your arguments easily overthrown by your group members?
A: Yes. It is because the problems in arguments are not in the evidence, but always
in the proof of the evidence.
Activity 3

Activity 3
Instructions



Pick up your role (group of supporters, opponents
and adjudicators) in debate. Discuss with your
group members to produce an agreed list. You
may find some evidence not shown in worksheet B.
Each group of supporters or opponents, will have
15 minutes to present their claims and 5 minutes to
rebut.
Adjudicators rate debaters’ performance
according to the following rubrics. You will
have 15 minutes to explain your rating and state
the decision at the end of the debate.
Rate the evidence using a scale from 1 to 5.
1
2
3
4
5
very weak
weak
adequate
strong
very
strong
need more
evidence
P 148
In order to have a strong argument, the following points should be considered.
a. Is there enough evidence to support you?
b. Is the evidence credible or convincing?
c. Is the evidence valid or correct?
Q: What are the components of an argument?
A: ARGUMENT = CLAIM + EVIDENCE
Claim is a thesis in an argument.
Adequate
evidence
P 149
Argument or claim should be supported by evidence.
Remarks: More information about GM food can be obtained from http://www.food.
gov.uk/multimedia/pdfs/gmbooklet.pdf.
Activity 2
(a) You may work in pairs to identify each of the following claims in worksheet A
as in favour or against GM crops, label them as for or against respectively.
(b) In addition, you should consider each of the following claims from the
perspectives concerning with human health, environment or economics. Label
them as HH, ENT, ECON respectively.
(c) Cut up worksheet A and B. Select evidence from worksheet B to support the
relevant claim. There will be more than one piece of evidence for most of the
arguments.
Answers
Claims
1. GM food is likely to cause human health
problems.
2. GM food is safe for humans.
3. GM foods will improve human health.
4. The risk to the ecosystem is unclear so the
precautionary principle should be used and GM
banned until far more research is carried out.
5. Introduced genes will cause serious damage to
food chains and the ecosystem.
6. GM will benefit the environment as less
herbicide and insecticide need to be used on GM
plants.
7. We have an obligation to use GM to increase
food supply and nutrition in poorer countries.
8. Farmers will be able to make more money and
sell cheaper food, therefore they should be allowed
to use GM.
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for/
Type
against
against HH
for
HH
for
HH
against ENT
Evidence
9. GM technology gives too much control over the food supply against ECON
to a few large multinational companies and should be publicly
funded.
10. GM has risks and benefits. Careful regulation is needed
against ENT/
otherwise the environment will bear all risks and GM
ECON
companies gain all the benefits.
Credit: Angela Melamed, The Nuffield Foundation (2005)
Activity 3
The class would be divided into 3 groups - supporters and opponents of GM crops as
well as the adjudicators. The group in support of GM crops will present their claims
and the corresponding evidences first. Then the opposition group may challenge the
claims and the evidences. The supporter group can rebut. Then the whole process
will go through once more with the opposition group. The adjudicators would
comment on the performance of the supporter group and the opposition group and
finally decide whether they would be supporters or opponents of GM crops.
Instructions
Pick up your role (group of supporters, opponents and adjudicators) in debate.
Discuss with your group members to produce an agreed list. You may find some
evidence not shown in worksheet B.
against ENT
Each group of supporters or opponents will have 15 minutes to present their claims
and 5 minutes to rebut.
Adjudicators rate debaters’ performance according to the following rubrics. You
will have 15 minutes to explain your rating and state the decision at the end of the
debate.
for
Rate the evidence using a scale from 1 to 5.
for
for
ENT
HH/
ECON
ECON
1
Very weak
Need more evidence
2
Weak
3
Adequate
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4
Strong
5
Very strong
Adequate evidence
Answers
Alternative topic for debate
Claims
1. GM food is likely to cause human health problems.
2. GM food is safe for humans.
3. GM food will improve human health.
4. The risk to the ecosystem is unclear so the precautionary
principle should be used and GM banned until far more
research is carried out.
5. Introduced genes will cause serious damage to food
chains and the ecosystem.
6. GM will benefit the environment as less herbicide and
insecticide need to be used on GM plants.
7. We have an obligation to use GM to increase food supply
and nutrition in poorer countries.
8. Farmers will be able to make more money and sell
cheaper food, therefore they should be allowed to use GM.
9. GM technology gives too much control over the food
supply to a few large multinational companies and should be
publicly funded.
10. GM has risks and benefits. Careful regulation is needed
otherwise the environment will bear all risks and GM
companies gain all the benefits.
for/ against
against
for
for
against
Type
HH
HH
HH
ENT
against
ENT
for
ENT
for
for
HH/
A, D, N, U
ECON
ECON F, G, I, U
against
ECON K, R, T, Y
against
ENT/ F, K, P, T,
ECON U, V, X
Credit: Angela Melamed, The Nuffield Foundation (2005)
Evidence
C, L
A, B, M
A, D, N, U
E, H, K,
Q, S, V,
X, Z
E, Q, V,
X, Z
I, W
Background
Animal testing is the use of non-human animals in scientific experimentation. The
testing is conducted inside universities, pharmaceutical companies and farms. Areas
of conducting animal testing cover genetics, developmental biology, behavioural
studies, organ transplantation, drug testing and cosmetics testing etc.
Debate: Is it morally acceptable to experiment on animals for human purposes?
The class can be divided into 3 groups. Each group should have supporters, opponents
as well as the adjudicators. According to your standpoint, supporters and opponents
should work together to list out all your supporting claims and evidences before
conducting debate. Adjudicators summarize what you hear in the debate and make
your decision.
You have 10 minutes to prepare the list.
Hints: You may consider the following aspects.
 Do humans have justifying testing?
 Are humans superior to animals or equals?
 Is it wrong to believe that animals have rights?
 Does animal testing have little to no impact on the environment?
 Are alternatives to animal testing inadequate?
 Are the sources of animals used in laboratories appropriate?
The above information is retrieved from the following website on 10 th Oct 2008.
http://wiki.idebate.org/index.php/Debate:Animal_Experimentation#Is_it_morally_
acceptable_to_experiment_on_animals_for_human_purposes.3F
Remarks: More information about animal testing can be obtained from http://www.
aph.gov.au/senate/committee/history/animalwelfare_ctte/animal_experimentation/
index.htm
P 152
P 153
Students’ Worksheet
Lesson 7 Arguments in Science
Activity 1
Use the resource listed below to search evidence for and against ‘genetically modified
(GM) food being safe for humans to eat’. Take your side according to the evidence
drawn. You will be required to present your argument to your group.
http://www.beep.ac.uk/content/392.0.html
(a) What kind of evidence can be used to support an argument?
(b) Does all evidence support one point of view only?
(c) How can you prevent your argument from easily overthrown by your group
members?
(d) What are the components of an argument?
(b) In addition, you should consider each of the following claims from the
perspectives concerning with human health, environment or economics. Label
them as HH, ENT, ECON respectively.
(c) Cut up worksheet A and B. Select evidence from worksheet B to support the
relevant claim. There will be more than one piece of evidence for most of the
arguments.
Activity 3
The class would be divided into 3 groups - supporters and opponents of GM crops as
well as the adjudicators. The group in support of GM crops will present their claims
and the corresponding evidences first. Then the opposition group may challenge the
claims and the evidences. The supporter group can rebut. Then the whole process
will go through once more with the opposition group. The adjudicators would
comment on the performance of the supporter group and the opposition group and
finally decide whether they would be supporters or opponents of GM crops.
Instructions
Pick up your role (group of supporters, opponents and adjudicators) in debate.
Discuss with your group members to produce an agreed list. You may find some
evidence not shown in worksheet B.
Each group of supporters or opponents will have 15 minutes to present their claims
and evidences, and 5 minutes to rebut.
Adjudicators rate debaters’ performance according to the following table. You will
have 10 minutes to explain your rating and make your decision at the end of the
debate.
Rate the evidence using a scale from 1 to 5.
1
2
3
very weak
weak
adequate
need more evidence
Activity 2
(a) You may work in pairs to identify each of the following claims in worksheet A
as in favour or against GM crops. Label them as for or against respectively.
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P 155
4
strong
5
very strong
adequate evidence
Worksheet A
Worksheet B
Claims
For / Against Type
1. GM food is likely to cause human health problems.
2. GM food is safe for humans.
3. GM food will improve human health.
4. The risk to the ecosystem is unclear so the precautionary
principle should be used and GM banned until far more research is
carried out.
5. Introduced genes will cause serious damage to food chains and
the ecosystem.
6. GM will benefit the environment as less herbicide and
insecticide need to be used on GM plants.
7. We have an obligation to use GM to increase food supply and
nutrition in poorer countries.
8. Farmers will be able to make more money and sell cheaper food,
therefore they should be allowed to use GM.
9. GM technology gives too much control over the food supply to a
few large multinational companies and should be publicly funded.
10. GM has risks and benefits. Careful regulation is needed
otherwise the environment will bear all risks and GM companies
gain all the benefits.
Evidences
A. No evidence of harm to human health from eating GM food exists
B. In the US more than half of all soya and maize is GM
C. Rats fed on potatoes which had been genetically modified to contain a plant
toxin became ill
D. GM rice has been developed to contain vitamin A
E. Laboratory studies showed that Monarch butterflies had a lower survival rate
when fed on GM plants
F. Yields of GM cotton containing insecticide are greater than yields of non-GM
cotton in the same conditions
G. The cost of insecticide is the main expense for cotton farmers
H. Insects gradually become resistant to most widely used insecticides
I. Fields with GM plants that are herbicide resistant need less frequent herbicide
spraying
J. In the UK extensive trials have shown that herbicide-tolerant maize causes less
damage to the environment than normal maize
K. Trials for food safety of GM crops are usually carried out by the companies
that have developed them, not by an independent body
L. There is some evidence that GM food may be allergenic to some sensitive
people
M. Cows fed on GM soya and maize showed no GM genes in their milk
N. It will be possible to develop GM plants that give better yields in arid or poor
soil
O. GM companies have decided not to market any GM crops in the UK at present
P. Farmers will be able to spray fields with herbicide more often without damage
to their crops
Q. Plant pollen can travel large distances
R. Almost no research has been done on developing GM plants that give better
yields in arid or salty soil
S. It is unclear whether wild plants which have crossed with GM crops will have
an advantage or a disadvantage in the wild
T. Large multinational companies have been given patents on many plant genes
U. The GM variety of many crops gives an increased yield
V. In the UK trials of GM crops showed that growing herbicide tolerant grapes
and beet reduces the number of butterflies and bees in the area
W. Insecticide spray always affects the areas surrounding the crops and runs off
into rivers causing further damage
X. The interdependence of all species of living organisms in an ecosystem means
that the results of changes in one species may have unpredictable consequences
Y. GM companies have been buying seed producing firms in Europe and in India
Z. It is known that genes can spread from crops to related wild plants
Type
Credit: Angela Melamed, The Nuffield Foundation (2005) (Worksheet A and B)
P 156
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Suggested Learning and Teaching Activities
Lesson 8Analogies in Science
Level of Students: S.1-S.2
Learning Objectives:
Students will
 be able to understand analogy in inference and its limitation;
 apply analogy to infer special property from a particular object to another
particular object;
 be able to appreciate how analogy contributes to the development of science.
Activity 3
15 min.
(Data of two solar system objects,
the Earth and the Mars)
Activity 4
15 min.
(Illustration of science concepts
with analogy)
Activity 5
15 min.
Supplementary activities:
Suggested Lesson Time: 90 min.
Prior knowledge of students:
S.1 students learnt the particle model at the end of the second term. The teacher
may ask the students a few related questions to check their understanding on the
particle model. Then the teacher may introduce to the students the use of analogy in
sicence.
15 min.
The focus of this activity is on the application
of analogy on scientific prediction
(a) The focus of this activity is on the use of
analogy to illustrate difficult science concepts
(b) There may be limits to analogy
The focus of this activity is on the
contribution of analogy in science and the
limits to analogy.
(a) The focus of this activity is to let students
appreciate the wonder of analogies leading to
scientific discoveries or inventions.
(b) Students are reminded that analogies are
used in many clinical researches and the final
success on humans depends on probability.
Focus Ideas:
If two things or objects, A and B have some similar properties, and A has other
special attribute, property W, we can possibly infer that B also has the attribute,
property W. Analogy is an inference from a particular object to another particular
object. For instance, a camera is compared to an eye.
Scientific analogies make people think creatively leading to many discoveries and
inventions. Analogies also help with the development, evaluation and exposition of
scientific theories, models and concepts. However, there are limitations to analogies
because analogies may create misconceptions to scientific concepts.
Suggested Learning and
Teaching Activities:
Lesson 8 Analogies in
Science
Activity 1
(A4 Paper Experiment)
Activity 2
(The story of doctor Sun
Simiao)
Time
allocation
Approx.
90 min.
15 min.
15 min.
Remarks
The students are divided into groups of 4-5 members to
carry out the activities.
This activity aims to motivate students to learn the
concept of analogy
(a). The focus of this activity is to let students
appreciate how analogy helps to solve medical
problems in the past;
(b). This activity also introduces to students the related
logic of analogy and the relationship among analogy,
induction and deduction in science.
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P 159
PowerPoint
Enhancing Thinking Skills in
Science Context
Lesson 8
Analogies in Science
Activity 1
Activity 2
You are given a piece of A4 paper and two paper
clips. Try to fold the piece of paper to support
the weight of as many books as you can (i.e. the
pile of books are placed on the folded paper).
Long time ago a patient suffered from a disease making
him unable to urinate. His belly was swelling more and
more and he was in great pain. His doctor, Sun Simiao
(孫思邈 AD 581-682) thought that his urinary tract must
have been blocked. He could not think of the treatment
right away and was very frustrated because his patient
might die soon.
 Why do you fold the piece of paper in such
way (any related science concepts or
principles)?
This cylindrical paper roll
acts like a pillar (an
example of analogy) and
can support heavy
weights, too.
What can a scallion do?
Activity 2
He then saw a boy playing music with a roasted
scallion (烤熟的蔥管) by blowing air through it. It
made him think of the idea to save the patient’s
life!
What was Dr Sun’s treatment?
The piece of paper is
folded to a ring-shaped
structure.
 In what way(s) are urinary tracts and
scallions in common?
What can a scallion do?
Hair band
Shape?
string
pen
The ring-shaped paper
roll acts like a pillar (an
example of analogy) and
can support heavy
weights.
Property /function?
The piece of paper is
folded to a cylindrical shaped structure.
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P 161
straw
shoelace
Vine
basket
 Dr Sun then saw a boy playing music with a
roasted scallion (烤熟的蔥管) by blowing air
through it.
 It made him think of the idea that he could insert
such a tube (by cutting one end of the tube
small and sharp) into the urinary tract of the
patient and the urine can be sucked out by
mouth.
 Finally he really did so and the patient was
saved.
Discussion questions:
Activity 3
Urinary tracts and scallions are similar.
Dr. Sun used analogy to find a solution
to the problem of his patient.
Below is the data of two solar
system objects, the Earth and the
Mars:
Surface
temperature
Analogy
Analogy
Average density
Object A and object B are similar in having
properties X1, X2, X3, ……
If two things or objects, A and B have some
similar properties, and A has other special
attribute, property W, we can possibly infer that
B also has the attribute, property W. Analogy is
an inference from a particular object to another
particular object.
Object A has property W.
It is most likely that Object B also has the
property W.
Relationship among analogy, induction
and deduction in science
Analogy
Generalisation
A: X1, X2, X3, ……; W
B: X1, X2, X3, ……
Therefore, B may have property W.
Deduction
Induction
Special attribute A
(particular facts or
ideas)
Analogy
Special attribute B
(particular facts or
ideas)
(reference: 《類比》王溢然，張耀久(2001))
P 162
Average 17
degree Celsius
5500 kg/m
3
-93 to -3 degree
Celsius
Special features
Earth
Mars (火星)
Shape
spherical
spherical
Moon
one moon
2 moons
Orbital period
1 earth year
(remarks: Neptune-164
earth year; Uranus-84
earth year)
Components of the
Atmosphere
78% nitrogen
21 % oxygen
1 % argon, water
vapour, carbon dioxide,
other inert gases
95.3 % Carbon dioxide
2.7 % nitrogen
1.6% argon
trace amounts of
oxygen, carbon
monoxide and water
vapour
Water
Abundant amount of
water
In 2007 scientists
discovered that the
south pole of Mars was
covered by dry ice and
cold water.
Methane
Released as metabolites
of living organisms
The presence of
methane was detected
in 2003.
3900 kg/m 3
Surface gravity
1.00 (Earth =
1.00)
0.38
Atmospheric
pressure
1.0 (Earth =
1.00)
0.007
Discussion questions:
1. What are the similar properties between the
Earth and Mars?
2. It is a very distinctive property of the Earth
that there are living creatures on the Earth.
Do you have great confidence to use Analogy
to argue that there would also be living things
on Mars? Please explain your answer.
P 163
1.9 earth year
Hydraulic analogy to explain electric circuit
Task 1
1. Fill in the blanks:
Wires  (
)
Potential (
)
Voltage (potential difference)  (
Current (
)
Resistor (
)
Wires
Electrical Potential
Voltage
)
Electric current
Light bulb
Pump
Reference website (analogy model):
http://www.ac.www.edu/~vawter/PhysicsNet/Topics/DCCurrent/WaterFlowAnalog.html
2. What are the limits to the
above hydraulic analogy?
Paddle
Water pressure
Water pipes
Difference in pressure
between two points
Water current
(b) Analogy leads to inventions
The importance of analogy in logic is that it helps
with divergent thinking and enhances creativity.
Many inventions were due to analogical thinking.
For instance, it was found that bats could fly freely
without hitting any obstacles in the dark. The
discovery of radars was through the analogy to
the sound wave detecting system of bats.
Dry cell
(c) Analogy provides logical foundation
Activity 5
We may ask the following questions ourselves:
for modeling experiments
Analogy is commonly used in simulation, which
in turn has been a very important process in
scientific research. For instance, scientists and
engineers usually use wind tunnels to carry out
investigations on aircrafts.
1. Name the contribution of analogy in science.
 In the hydraulic analogy model water would leak
out if there is a hole in the water pipe. Electric
charge would not “leak out” if there is a hole in
the wires.
 The pump of the above hydraulic analogy model
does not need energy to work with.
2. What are the limits to analogy?
Wind tunnel
1. Name the contribution of analogy in science.
1. Name the contribution of analogy in science.

(a)Analogy helps with the development of new concepts and
hypotheses in science
Though the fact that a conclusion inferred from analogy may
be right is due to probability, analogy is still an important
method to form new concepts especially during the initial stage
of concept or theory development. In science many important
theories started with some hypotheses formulated by
analogies and then supported by empirically evidence.


P 164
However, new knowledge generated through analogy must be
compared with prior knowledge in order to have a strong
analogical argument. The inferred properties/ relationship
between 2 objects using analogy method may or may not be true
and it all depends on probability. In general, the relevance of
the similarities is important.
Moreover, the number of relevant similarities also matters. The
greater the number of relevant and fundamental properties
between the 2 objects, the stronger the analogical relationship
between the two objects.
Furthermore, if there are incompatibility between the inferred
properties and the properties of the analogue, the strength of the
analogical inference is weak.
2. What are the limits to analogy?
(a) Analogy helps explain science concepts well but can
create misconceptions.
An analogy is sometimes valid for understanding part of a
scientific process but it may not be able to be applied to the
process as a whole.
Credit: NASA
(b) The reliability of the conclusion drawn from analogy
depends on empirical evidence.
P 165
1. Search for examples of analogies
leading to scientific discoveries or
inventions.
Supplementary activities:
 Alexander Graham Bell used analogies to invent
telephones. Bell’s idea for the telephone was
sparked by the human ear structure.
1. Search for examples of analogies
leading to scientific discoveries or
inventions.
 Scientists tried to use lines to represent lines of
force surrounding a bar magnet.
 The legend that Archimedes (c. 287-212 BC) used
analogy to uncover a fraud against King Hieron II of
Syracuse using his principle of buoyancy.
Teachers’ Reference
Lesson 8Analogies in Science
Learning Objectives:
Students will
 be able to understand analogy in inference and its limitation;
 apply analogy to infer special property from a particular object to another
particular object;
 be able to appreciate how analogy contributes to the development of science.
Suggested Lesson Time: about 90 min.
2. Challenging Problem
Discussion Question:
According to a press release dated on 4 June 2008, a leading
microbiologist Professor Yuen Kwok-yung, the University of Hong Kong,
discovered ways to increase the survival rate of mice infected with H5N1.
In the research mice were first given 1000 times lethal dose of H5N1.
(a) What is the analogy reasoning of
carrying out the clinical trial?
(b) Please comment on the chance of
success of the clinical trial.
Then after 48 hours one group of mice were given the antiviral drug,
zanamivir while another group of mice was given the antiviral drug
zanamivir and two non-steroidal anti-inflammatory agents, celecoxib and
mesalazine. It was found that the survival rate of mice infected with lethal
doses of the bird flu virus, H5N1 could increase from 13.3 per cent
(zanamivir alone) to 53.3 per cent (i.e. fourfold).
Clinical trials with these three drugs would be carried out later to
investigate the effect on human infected with H5N1.
Focus Ideas:
If two things or objects, A and B have some similar properties, and A has other
special attribute, property W, we can possibly infer that B also has the attribute,
property W. Analogy is an inference from a particular object to another particular
object. For instance, a camera is compared to an eye.
Scientific analogies make people think creatively leading to many discoveries and
inventions. Analogies also help with the development, evaluation and exposition of
scientific theories, models and concepts. However, there are limitations to analogies
because analogies may create misconceptions to science concepts.
Activity 1
You are given a piece of A4 paper and two paper clips. Try to fold the piece of paper
to support the weight of as many books as you can (i.e. the pile of books are placed
on the folded paper). Why do you fold the piece of paper in such way (any related
science concepts or principles)?
(b) Please comment on the chance of success
of the clinical trial.
(a) What is the analogy reasoning of carrying
out the clinical trial?
 The experimental data shows that although the drug
cocktail works in mice, the treatment may not work
on infected human. Mice and human share many
biological similarities but there are still a lot of
biological differences. It is uncertain that the drug
cocktail works on infected human.
 Mice have many similarities to humans.
 Mice infected with H5N1 survive better with the
new treatment (“drug cocktail”).
 Human infected with H5N1 may survive better
with the new treatment (“drug cocktail”), too.
P 166
Note:
Students may roll the paper to a cylinder-shaped or a ring-shaped struture and use
the paper clips to fix the shape. Both structures can support the weight of several
books by adjusting the centre of mass along the middle line of the cylinder or the
ring. Such structures are similar to pillars commonly used in buildings (an example
of analogy) to support heavy weights.
P 167
Activity 2
Long time ago a patient suffered from a disease making him unable to urinate. His
belly was swelling more and more and he was in great pain. His doctor, Sun Simiao
( AD 581-682) thought that his urinary tract must have been blocked. He could not
think of the treatment right away and was very frustrated because his patient might
die soon.
Relationship among Analogy, Induction and Deduction in Science
Generalization
He then saw a boy playing music with a roasted scallion (烤熟的蔥管) by blowing
air through it. It made him think of the idea that he could insert such a tube (by
cutting one end of the tube small and sharp) into the urinary tract of the patient and
the urine can be sucked out by mouth. Finally he really did so and the patient was
saved.
Induction
Discussion questions:
In what way(s) are urinary tracts and scallions similar? Then use a diagram to show
how (the logic of thinking) Dr. Sun arrived at his solution to the problem of his
patient.
Note:
Analogy
If two things or objects, A and B have some similar properties, and A has other special
attribute, property W, we can possibly infer that B also has the attribute, property W.
Analogy is an inference from a particular object to another particular object.
Object A and object B are similar in having properties X1, X2, X3, ……
Object A has property W.
It is most likely that Object B also has the property W.
A: X1, X2, X3, ……; W
B: X1, X2, X3, ……
Therefore, B may have property W.
P 168
Special Attribute A
Deduction
Analogy
Special Attribute B
(particular facts or ideas)
(particular facts or ideas)
reference:《類比》王溢然，張耀久(2001)
Activity 3
Below is the data of two solar system objects, the Earth and the Mars:
Special Features
Earth
Mars (火星)
Shape
spherical
spherical
Moon
one moon
2 moons
Orbital Period
1 earth year
1.9 earth year
(remarks: Neptune-164 earth
year, Uranus-84 earth year)
Surface temperature
Average 17 degree Celsius
Average density
5500kg/m3
3900kg/m3
Surface gravity
1.00 (Earth = 1.00)
0.38
P 169
Atmospheric pressure
Components of the
Atmosphere
1.0 (Earth = 1.00)
78% nitrogen
21 % oxygen
1 % argon, water vapour,
carbon dioxide, other inert
gases
Water
Abundant amount of water
Methane
Released as metabolites of
living organisms
0.007
95.3 % Carbon dioxide
2.7 % nitrogen
1.6% argon
trace amounts of oxygen,
carbon monoxide and water
vapour
In 2007 scientists discovered
that the south pole of Mars was
covered by dry ice and cold
water.
The presence of methane was
detected in 2003.
Discussion questions:
1. What are the similar properties between the Earth and Mars?
2. It is a very distinctive property of the Earth that there are living creatures on the
Earth. Do you have great confidence to use Analogy to argue that there would
also be living things on Mars? Please explain your answer.
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P 171
The analogical relationship is represented by the symbol 
Task 4
1. Fill in the blanks:
Wires  (water pipes)
Potential  (water pressure)
Voltage (potential difference)  (difference in pressure between two points)
Current  (quantity of water flowing through over time)
Resistor  (all pipes have resistance)
2. What are the limits to the above hydraulic analogy?
We may ask the following questions ourselves:
 In the hydraulic analogy model water would leak out if there is a hole in the
water pipe. Electric charge would not “leak out” if there is a hole in the wires.
 The pump of the above hydraulic analogy model does not need energy to work
with.
(b) Analogy leads to inventions
The importance of analogy in logic is that it helps with divergent thinking and
enhances creativity. Many inventions were due to analogical thinking. For instance,
it was found that bats could fly freely without hitting any obstacles in the dark. The
discovery of radars was through the analogy to the sound wave detecting system of
bats.
(c) Analogy provides logical foundation for modeling experiments
Analogy is commonly used in simulation, which in turn has been a very important
process in scientific research. For instance, scientists and engineers usually use
wind tunnels to carry out investigations on aircrafts.
2. What are the limits to analogy?
Activity 5
1. Name the contribution of analogy in science.
(a) Analogy helps explain science concepts well but can create misconceptions.
An analogy is sometimes valid for understanding part of a science process but
it may not be able to be applied to the process as a whole.
Note:
Contribution of Analogy in Science
(b) The reliability of the conclusion drawn from analogy depends on empirical
evidence.
(a) Analogy helps with the development of new concepts and hypotheses in science
Though the fact that a conclusion inferred from analogy may be right is due to
probability, analogy is still an important method to form new concepts especially
during the initial stage of concept or theory development. In science, many important
theories started with some hypotheses formulated by analogies and then supported
by empirically evidence.
However, new knowledge generated through analogy must be compared with prior
knowledge in order to have a strong analogical argument. The inferred properties/
relationship between 2 objects using analogy method may or may not be true and it
all depends on probability. In general, the relevance of the similarities is important.
Moreover, the number of relevant similarities also matters. The greater the number of
relevant and fundamental properties between the 2 objects, the stronger the analogical
relationship between the two objects. Furthermore, if there are incompatibility
between the inferred properties and the properties of the analogue, the strength of
the analogical inference is weak.
P 172
P 173
Supplementary activities:
 Human infected with H5N1 may survive better with the new treatment
(“drug cocktail”), too.
1. Search for examples of analogies leading to scientific discoveries or inventions.
Notes:
 Alexander Graham Bell used analogies to invent telephones. Bell’s idea for the
telephone was sparked by the human ear structure.
 Scientists tried to use lines to represent lines of force surrounding a bar magnet.
 The legend that Archimedes (c. 287-212 BC) used analogy to uncover a fraud
against King Hieron II of Syracuse using his principle of buoyancy.
(reference: http://www.juliantrubin.com/bigten/archimedesprinciple.html)
(b) Please comment on the chance of success of the clinical trial.
Though the experimental data shows that the drug cocktail works in mice, the
treatment may not work on infected human. Mice and human share many biological
similarities but there are still a lot of biological differences. It is uncertain that the
drug cocktail works on infected human.
2. Challenging Problem
According to a press release dated on 4 June 2008 a leading microbiologist, Professor
Yuen Kwok-yung, the University of Hong Kong, discovered ways to increase the
survival rate of mice infected with H5N1.
In the research mice were first given 1000 times lethal dose of H5N1. Then after
48 hours one group of mice were given the antiviral drug, zanamivir while another
group of mice was given the antiviral drug zanamivir and two non-steroidal antiinflammatory agents, celecoxib and mesalazine. It was found that the survival rate
of mice infected with lethal doses of the bird flu virus, H5N1 could increase from
13.3 per cent (zanamivir alone) to 53.3 per cent (i.e. fourfold).
Clinical trials with these three drugs would be carried out later to investigate the
effect on human infected with H5N1.
Discussion Question:
(a) What is the analogy reasoning of carrying out the clinical trial?
Suggested answer:
 Mice have many similarities to humans.
 Mice infected with H5N1 survive better with the new treatment
(“drug cocktail”).
P 174
P 175
Students’ Worksheet
Lesson 8
Activity 3
Below are the data of two solar system objects, the Earth and the Mars:
Analogies in Science
Activity 1
You are given a piece of A4 paper and two paper clips. Try to fold the piece of paper
to support the weight of as many books as you can (i.e. the pile of books are placed
on the folded paper). Why do you fold the piece of paper in such way (any related
science concepts or principles)?
Activity 2
Long time ago a patient suffered from a disease making him unable to urinate. His
belly was swelling more and more and he was in great pain. His doctor, Sun Simiao
(孫思邈 AD 581-682) thought that his urinary tract must have been blocked. He
could not think of the treatment right away and was very frustrated because his
patient might die soon.
He then saw a boy playing music with a roasted scallion (烤熟的蔥管) by blowing
air through it. It made him think of the idea that he could insert such a tube (by
cutting one end of the tube small and sharp) into the urinary tract of the patient and
the urine can be sucked out by the mouth. Finally he really did so and the patient
was saved.
Discussion questions:
In what way(s) are urinary tracts and scallions similar? Then use a diagram to show
how (the logic of thinking) Dr. Sun arrived at his solution to the problem of his
patient.
P 176
Special features
Earth
Mars:
Shape
Moon
Orbital period
spherical
one moon
1 earth year
Surface temperature
Average density
Average 17 degree Celsius
spherical
2 moons
1.9 earth year
(remarks: Neptune-164
earth year; Uranus-84
earth year)
-93 to -3 degree Celsius
3900 kg/
3
Surface gravity
Atmospheric pressure
Components of the
Atmosphere
5500 kg/ m
1.00 (Earth = 1.00)
1.0 (Earth = 1.00)
78% nitrogen
21 % oxygen
1 % argon, water vapour, carbon
dioxide, other inert gases
Water
Abundant amount of water
Methane
Released as metabolites of living
organisms
P 177
m3
0.38
0.007
95.3 % Carbon dioxide
2.7 % nitrogen
1.6% argon
trace amounts of oxygen,
carbon monoxide and
water vapour
In 2007 scientists
discovered that the
south pole of Mars was
covered by dry ice and
cold water.
The presence of methane
was detected in 2003.
Discussion questions:
1. What are the similar properties between the Earth and Mars?
2. It is a very distinctive property of the Earth that there are living creatures on the
Earth. Do you have great confidence to use Analogy to argue that there would
also be living things on Mars? Please explain your answer.
P 178
P 179
Voltage (potential difference)  ( )
Current  (
)
Resistor  (
)
Reference website (analogy model): http://www.ac.wwu.edu/~vawter/PhysicsNet/
Topics/DC-Current/WaterFlowAnalog.html
2. What are the limits to analogy?
2. What are the limits to the above hydraulic analogy?
Supplementary activities:
1. Search for examples of analogies leading to scientific discoveries or inventions.
Activity 5
1. Name the contribution of analogy in science.
P 180
P 181
2. Challenging Problem
According to a press release dated on 4 June 2008 a leading microbiologist, Professor
Yuen Kwok-yung, the University of Hong Kong, discovered ways to increase the
survival rate of mice infected with H5N1.
Snapshots of Lesson 8
In the research mice were first given 1000 times lethal dose of H5N1. Then after
48 hours one group of mice were given the antiviral drug, zanamivir while another
group of mice was given the antiviral drug zanamivir and two non-steroidal antiinflammatory agents, celecoxib and mesalazine. It was found that the survival rate
of mice infected with lethal doses of the bird flu virus, H5N1 could increase from
13.3 per cent (zanamivir alone) to 53.3 per cent (i.e. fourfold).
Clinical trials with these three drugs would be carried out later to investigate the
effect on human infected with H5N1.
Discussion Question:
(a) What is the analogy reasoning of carrying out the clinical trial?
(b) Please comment on the chance of success of the clinical trial.
P 182
P 183
Suggested Learning and Teaching Activities
Suggested Learning and Teaching
Activities:
Lesson 9 Pseudoscience
Lesson 9Pseudoscience
Level of Students: S.1-S.2
Activity 1
(The Fifth Great Invention of China)
Learning Objectives:
Students will
 be able to distinguish between science and pseudoscience;
 identify flaws in pseudoscience.
Activity 2
(SUPER Water)
Time
allocation
Approx.
90 min.
20 min.
Suggested Lesson Time: 1 period (about 90 min.)
Focus Ideas:
It is important to be able to distinguish between science and pseudoscience.
Pseudoscience lacks the criteria of evidence, the design of meaningful experiments,
the weighing of possibilities, the testing of hypotheses, the establishment of theories,
the many aspects of scientific methods that make it possible to draw reliable
conclusions about the physical universe. From time to time people are bombarded
by the mass media of news and claims of pseudoscience. People need a scientific
habit of mind to distinguish between true science and pseudoscience.
Prior knowledge of students:
Students often come across advertisements on topics like healthy foods and weight
reduction programmes. Many claims of such advertisements involve science
terminology. The teacher may ask the students a few related questions to check their
understanding on the reliability of such claims.
P 184
P 185
Remarks
The students are divided into groups of
4-5 members to carry out the activities.
(a). The focus of this activity is to
let students know how people can be
cheated by pseudoscience;
(b). Students are motivated to think
deeply on the characteristics of
pseudoscience.
(a). Students are required to act out the
different roles (customers, salesmen,
scientists, representatives of the
Consumer Council) so as to have a better
understanding of pseudoscience;
(b). Students should be able to
distinguish between science and
pseudoscience after the lesson.
PowerPoint
Enhancing Thinking Skills in
Science Context
Lesson 9
Activity 1
Read the following news:
Pseudoscience
The Fifth Great Invention of China
Activity 1
Activity 1
A man from China called Wong Hung Shing claimed that he
discovered the technology to convert water to fuel oil on 7
November 1983. He first prepared a chief formulation that
contained a small amount of alkyne (a compound that can be
burned) and then he added this chief formulation to a large amount
of water (ratio: 1/100,000 volume/volume). A water-based fuel was
claimed to be created that could be a substitute for petrol and the
cost was very cheap. He said that the water-based fuel could be
produced very easily by a simple machine. One tonne of the chief
formulation could be produced in 20 minutes and one tonne of the
chief formulation could in turn produce 10 tonnes or more of the
water-based fuel.
The mass media reported Wong’s invention and he demonstrated
his technology to some famous scientists in China. Some
presidents of the universities and senior government officials
believed his invention doubt. Some mass media claimed Wong’s
invention as the Fifth Great Invention of China.
Discussion questions:
1)
2)
3)
1. What was Wong’s invention?
What was Wong’s invention?
What were the evidences (or what seemed to be the
evidences) that supported Wong’s invention?
Were the evidences you read from the news sufficient to
make you believe in Wong’s invention? If not, what other
evidences or information you would like to get hold of before
A very cheap water-based fuel produced by adding small
amount of alkyne to large amount of water in the ratio
1:100,000 (V/V).
2.
1. Were the evidences you read from the news sufficient to make
you believe in Wong’s invention? If not, what other evidences or
information you would like to get hold of before you can believe in
Wong’s invention?
What were the evidences (or what seemed to be the
evidences) that supported Wong’s invention?
a. He demonstrated his technology to some famous scientists in
China. [It did not tell whether those famous scientists believed his
invention or not]
b. Some presidents of the universities and senior government officials
believed in his invention without a doubt. [The newspaper only told us
that there were some people of high rank believed in Wong’s
invention but there were also some or many people who did not
believe in Wong’s invention]
c. Some mass media claimed Wong’s invention as the Fifth Great
Invention of China.
[We do not know the credibility of the mass media]
a. Background of the “inventor” including his qualifications and career;
b. His experimental procedure and exact formulation;
c. Can we repeat his experiment?
d. Can his invention be tested by famous universities, the
government or accredited organisations?
e. Any theoretical backup to his invention? Can we use existent
scientific concepts, theories, principles or laws to explain the
mechanism of his invention?
Background of Wong Hung Shing
Commercial Interests / Corruptions / Flaws?
Wong was born in China and received 4-year’s
schooling. He had been a carpenter, soldier
and a bus driver before he invented the waterbased fuel.
Wong’s invention was widely reported in the mass media. He
flew to many places like Beijing, Shanghai to demonstrate his
invention. He was then appointed the head of the newly
established Energy Institute of Hei Long Jiang (黑龍江). In
1987 he was commissioned RMB$600,000 (人民幣) to
produce the water-based fuel at He Bei (河北). However,
more and more people became skeptical about his invention
as time went by. He was finally caught in 1987 and sentenced
to 10-year imprisonment.
Activity 2
Reflection questions:
Read the following advertisement found in a
newspaper:
1. Can you suggest some reasons why people believed
in Wong’s invention?
2. How do we know that Wong’s “invention” is not real
science? Explain your answer.
you can believe in Wong’s invention?
P 186
P 187
SUPER Company has a water filter that can convert tap water to
SUPER WATER. SUPER Water can change ordinary water to
smaller water clusters. These water clusters can pass easily
through ion channels of cells. Hence, water can be absorbed
faster than ordinary water molecules to keep our skin moist. The
pH of the SUPER WATER is 9.5. Alkaline water can prevent
people from constipation and long-term diarrhea.
S UP E R
Water
P s eudos cience
Pseudoscience
SUPER Water
False
 a set of beliefs about the world incorrectly
thought to be scientific
 a certain method, theory, or practice that
claims to be scientific but fails to adhere to the
basic requirements of the scientific method.
knowledge
 more likely to be driven by ideological, cultural,
or commercial goals.
The dissolved oxygen content of SUPER WATER is also greater
than that of ordinary tap water. The higher dissolved oxygen
content can improve health because it can increase the metabolic
rate of cells and hence enhancing the immunity of the body.
Characteristics of Pseudoscience
Characteristics of Pseudoscience
SUPER Water
Change water into smaller water
molecule clusters
SUPER WATER Filter was invented by an expert of water
science, Dr. Kwun Lee. He is the chairman of International
Research Laboratory on Water Science since 2001.
SUPER
Water
Alkaline water
The SUPER WATER filter has been accredited by NSF. The
cost of the SUPER WATER Filter was HK$6,000. The filter
core needs to be changed every year and the cost is
HK$500.
No concrete research findings from
other scientists in the following
days support the claim or theory
Claim not supported by scientific research
Accredited by NSF
Higher dissolved oxygen content
Contradict with existent science
knowledge, theories, principles, laws…
The findings are usually for
commercial use - selling
questionable products for
big profits
Results not reproduced or verified
Unclear experimental procedure
Task 1:
1.Do you believe the claim? Suppose you are
Customers
- a customer,
explain whether you believe the claim of SUPER Water
filter or not.
-a salesman of the SUPER company, how will you promote
the SUPER Water filter to your customers?
-a scientist, tell people with scientific evidences or sound
reasons whether you support the claim of SUPER Water
filter or not.
-a representative from the Consumer Council, give advice
to the consumers on the claim of SUPER Company on
SUPER water.
Scientists
Salesman of the SUPER COMPANY
Representatives from the Consumer Council
P 188


The company uses a lot of scientific terms (water
clusters, ion channels, cells, pH, dissolved
oxygen content, metabolic rate, immunity) to
describe the special feature and function of its
filter. The use of such scientific terms may make
people think that the claim is scientific. However,
how true the claim is needs further evidence or
research findings from other scientists. Now
there is no further information provided by the
company.
P 189
The company told us that the product was invented
by an expert of water science and the product has
been accredited by an international organization NSF.
We may check more information about the credibility
of Dr Kwun Lee and the International Research
Laboratory on Water Science by searching the
internet. If Dr Kwun Lee has little or no research
publication in high standard journals or the scale of
the International Research Laboratory on Water
Science is very small (say only one chairman and no
other staff), the evidence of the claim would be weak.

Will the accreditation of NSF affect your decision to
believe the claim of SUPER WATER Filter? (Remarks:
NSF stands for U.S. National Sanitation Foundation
Standard) The accreditation of NSF is irrelevant to the
claim of the product. Accreditation by NSF only
shows that the production of the product matches a
set of regulations set out by the NSF. However, NSF
is NOT an organisation that is responsible to test or
verify the claim of the product.
Science
Pseudoscience
The claim is testable and
supported by scientific research
recorded in high standard
scientific journals.
The claim is not testable and there
is no support from scientific
research recorded in high standard
scientific journals
The finding does not usually
contradict existing scientific
knowledge, theories, principles
and laws.
The findings usually contradict
existing scientific knowledge,
theories, principles and laws.
The claim is not vague and the
experimental procedure is clearly
written and the result can be
reproduced by other scientists.
The claim uses vague language
and the result cannot be
reproduced or verified. The exact
procedure of the experiment is not
clearly provided . Other people
cannot figure out what has been
done and how it was done.
Teachers’ Reference
Lesson 9Pseudoscience
Learning Objectives:
Students will
 be able to distinguish between science and pseudoscience;
 identify flaws in pseudoscience.
Suggested Lesson Time: 1 period (about 90 min.)
Focus Ideas:
Science
Pseudoscience
As time goes by, more
research findings from other
scientists give more evidences
to support the claim or the
theory.
No concrete research findings
from other scientists in the
following days support the
claim or the theory.
Pseudoscience explains away
or ignores falsifying evidence.
The product of the application
of the science must be tested
thoroughly before marketing.
The findings are usually for
selling commercial products
with big profits.
Examples of Pseudoscience
Astrology
Reasons that Astrology is not considered as real science
are as follows:
 Astrological interpretations and prediction are not
based on science theories, principles or laws but from
astrological theories.
 Astrologers do not conduct carefully controlled
experiments to test astrological theories.
 Astrologers use vague language to explain and predict
things as well as to explain away wrong prediction.
Some personality descriptions are very general and fit
nearly everyone.
It is important to be able to distinguish between science and pseudoscience.
Pseudoscience lacks the criteria of evidence, the design of meaningful experiments,
the weighing of possibilities, the testing of hypotheses, the establishment of theories,
the many aspects of scientific methods that make it possible to draw reliable
conclusions about the physical universe. From time to time people are bombarded
by the mass media of news and claims of pseudoscience. People need a scientific
habit of mind to distinguish between true science and pseudoscience.
Activity 1
Read the following news:
The Fifth Great Invention of China
A man called Wong Hung Shing claimed that he discovered the technology to convert
water to fuel oil on 7 November, 1983 in China. He first prepared a chief formulation
that contained a small amount of alkyne (a compound that can be burned) and then
he added this chief formulation to a large amount of water (ratio: 1/100,000 volume/
volume). A water-based fuel was claimed to be created that could be a substitute
for petrol and the cost was very cheap. He said that the water-based fuel could be
produced very easily by a simple machine. One tonne of the chief formulation could
be produced in 20 minutes and one tonne of the chief formulation could in turn
produce 10 tonnes or more of the water-based fuel.
Reference:
 Gregory Bassham, et al., Critical
Thinking: A Students’ Introduction,
3rd ed. (New York: McGraw-Hill
Higher Education, 2008)
 《選擇》月刊第357期(「神奇」水機健康
聲稱備受質疑)
The mass media reported Wong’s invention and he demonstrated his technology to
some famous scientists in China. Some presidents of the universities and senior
P 190
P 191
government officials believed his invention without doubt. Some mass media
claimed Wong’s invention as the Fifth Great Invention of China.
For or against existent Science Concepts, Theories, Principles and Laws
His invention is against the law of conservation of energy.
Discussion questions:
Commercial Interests / Corruptions / Flaws?
Wong’s invention was widely reported in the mass media. He flew to many places
like Beijing, Shanghai to demonstrate his invention. He was then appointed the
head of the newly established Energy Institute of Hei Long Jiang (黑龍江). In 1987
he was commissioned 600,000 Ren Min Bi (人民幣) to produce the water-based
fuel at He Bei (河北). However, more and more people became skeptical about his
invention as time went by. He was finally caught in 1987 and sentenced to 10-year’s
imprisonment.
1. What was Wong’s invention?
[A very cheap water-based fuel produced by adding small amount of alkyne to large
amount of water in the ratio 1:100,000 (V/V).]
2. What were the evidences (or what seemed to be the evidences) that supported
Wong’s invention?
a. He demonstrated his technology to some famous scientists in China. [It did not
tell whether those famous scientists believed his invention or not]
b. Some presidents of the universities and senior government officials believed his
invention without doubt. [The newspaper only told us that there were some
people of high rank believed in Wong’s invention but there were also some or
many people who did not believe in Wong’s invention]
c. Some mass media claimed Wong’s invention as the Fifth Great Invention of
China.[We do not know the credibility of the mass media]
Reflection questions:
1. Can you suggest some reasons why people believed in Wong’s invention?
2. How do we know that Wong’s “invention” is not real science?
Explain your answer.
3. Were the evidences you read from the news sufficient to make you believe in
Wong’s invention? If not, what other evidences or information you would like to get
hold of before you can believe in Wong’s invention?
a. Background of the “inventor” including his qualifications and career;
b. His experimental procedure and exact formulation;
c. Can we repeat his experiment?
d. Can his invention be tested by famous universities, the government or accredited
organisations?
e. Any theoretical backup to his invention? Can we use existent science concepts,
theories, principles or laws to explain the mechanism of his invention?
Background of Wong Hung Shing
Wong was born in China and received 4-year’s schooling. He had been a carpenter,
soldier and a bus driver before he invented the water-based fuel.
P 192
P 193
Activity 2
Read the following advertisement found in a newspaper:
SUPER Water
SUPER Company has a water filter that can convert tap water to SUPER WATER.
SUPER Water can change ordinary water to smaller water clusters. These water
clusters can pass easily through ion channels of cells. Hence, water can be absorbed
faster than ordinary water molecules to keep our skin moist. The pH of the SUPER
WATER is 9.5. Alkaline water can prevent people from constipation and long-term
diarrhea.
The dissolved oxygen content of SUPER WATER is also greater than that or dinary
tap water. The higher dissolved oxygen content can improve health because it can
increase the metabolic rate of cells and hence enhancing the immunity of the body.
SUPER WATER Filter was invented by Dr. Kwun Lee who was an expert of water
science and he is the chairman of International Research Laboratory on Water Science
since 2001.
The SUPER WATER filter has been accredited by NSF. The cost of the SUPER
WATER Filter was HK$6,000. The filter core needs to be changed every year and
the cost is HK$500.
Task:
1. Do you believe the claim? Suppose you are
- a customer, explain whether you believe the claim of SUPER Water filter or not.
- a salesman of the SUPER company, how will you promote the SUPER Water
filter to your customers?
- a scientist, tell people with scientific evidences or sound reasons whether you
support the claim of SUPER Water filter or not.
- a representative from the Consumer Council, give advice to the consumers on the
claim of SUPER Company on SUPER water.
Teacher Notes:
(a) The company uses a lot of scientific terms (water clusters, ion channels, cells, pH,
dissolved oxygen content, metabolic rate, immunity) to describe the special feature
and function of its filter. The use of such scientific terms may make people think
that the claim is scientific. However, how true the claim is needs further evidence or
research findings from other scientists. Now there is no further information provided
by the company.
P 194
(b) The company told us that the product was invented by an expert of water science
and the product has been accredited by an international organisation NSF. We may
check more information about the credibility of Dr Kwun Lee and the International
Research Laboratory on Water Science by searching the internet. If Dr Kwun Lee
has little or no research publication in high standard journals or the scale of the
International Research Laboratory on Water Science is very small (say only one
chairman and no other staff) the evidence of the claim would be weak.
(c) Will the accreditation of NSF affect your decision to believe the claim of SUPER
WATER Filter? (Remarks: NSF stands for U.S. National Sanitation Foundation
Standard) This question aims to let students see how relevant the accreditation of
NSF to support the claim of the product. Accreditation by NSF only shows that the
production of the product matches a set of regulations set out by the NSF. However,
NSF is NOT an organisation that is responsible to test or verify the claim of the
product.
2. Compare science and pseudoscience.
Science
1. The claim is testable and supported by
scientific research recorded in high standard
scientific journals.
Pseudoscience
The claim is not testable and there is no
support from scientific research recorded in
high standard scientific journals.
2. The finding does not usually contradict
existing science knowledge, theories,
principles and laws.
The findings usually contradict existing
scientific knowledge, theories, principles and
laws.
3. The claim is not vague and the experimental The claim uses vague language and the result
procedure is clearly written and the result can cannot be reproduced or verified. The exact
be reproduced by other scientists.
procedure of the experiment is not clearly
provided. Other people cannot figure out
what has been done and how it was done.
4. As time goes by, more research findings
from other scientists give more evidence to
support the claim or the theory.
No concrete research findings from other
scientists in the following days support the
claim or the theory. Pseudoscience explains
away or ignores falsifying evidence.
5. The product of the application of the science The findings are usually for selling
must be tested thoroughly before marketing.
commercial products with big profits.
P 195
Examples of Pseudoscience
Students’ Worksheet
Astrology
Lesson 9Pseudoscience
Reasons that Astrology is not considered as real science are as follows:
a. Astrological interpretations and prediction are not based on scientific theories,
principles or laws but from astrological theories.
b. Astrologers do not conduct carefully controlled experiments to test astrological
theories.
c. Astrologers use vague language to explain and predict things as well as to
explain away wrong prediction. Some personality descriptions are very general
and fit nearly everyone.
Reference:
Gregory Bassham, et al., Critical Thinking: A Students’ Introduction, 3rd ed. (New
York: McGraw-Hill Higher Education, 2008)
《選擇》月刊第357期(「神奇」水機健康聲稱備受質疑)
Activity 1
Read the following news:
The Fifth Great Invention of China
A man in China called Wong Hung Shing claimed that he discovered the technology to
convert water to fuel oil on 7 November, 1983. He first prepared a chief formulation
that contained a small amount of alkyne (a compound that can be burned) and then
he added this chief formulation to a large amount of water (ratio: 1/100,000 volume/
volume). A water-based fuel was claimed to be created that could be a substitute
for petrol and the cost was very cheap. He said that the water-based fuel could be
produced very easily by a simple machine. One tonne of the chief formulation could
be produced in 20 minutes and one tonne of the chief formulation could in turn
produce 10 tonnes or more of the water-based fuel.
The mass media reported Wong’s invention and he demonstrated his technology to
some famous scientists in China. Some presidents of the universities and senior
government officials believed in his invention without doubt. Some mass media
claimed Wong’s invention as the Fifth Great Invention of China.
Discussion questions:
1. What was Wong’s invention?
2. What were the evidences (or what seemed to be the evidences) that supported
Wong’s invention?
P 196
P 197
3. Were the evidences you read from the news sufficient to make you believe in
Wong’s invention? If not, what other evidences or information you would like
to get hold of before you can believe in Wong’s invention?
Activity 2
Read the following advertisement found in a newspaper:
SUPER Water
SUPER Company has a water filter that can convert tap water to SUPER WATER.
SUPER Water can change ordinary water to smaller water clusters. These water
clusters can pass easily through ion channels of cells. Hence, water can be absorbed
faster than ordinary water molecules to keep our skin moist. The pH of the SUPER
WATER is 9.5. Alkaline water can prevent people from constipation and long-term
diarrhea.
The dissolved oxygen content of SUPER WATER is also greater than that of ordinary
tap water. The higher dissolved oxygen content can improve health because it can
increase the metabolic rate of cells and hence enhancing the immunity of the body.
SUPER WATER Filter was invented by Dr. Kwun Lee who was an expert of water
science and he is the chairman of International Research Laboratory on Water Science
since 2001.
The SUPER WATER filter has been accredited by NSF. The cost of the SUPER
WATER Filter was HK$6,000. The filter core needs to be changed every year and
the cost is HK$500.
Task:
1. Do you believe the claim? Suppose you are
- a customer, explain whether you believe the claim of SUPER Water filter or not.
- a salesman of the SUPER company, how will you promote the SUPER Water
filter to your customers?
- a scientist, tell people with scientific evidences or sound reasons whether you
support the claim of SUPER Water filter or not.
- a representative from the Consumer Council, give advice to the consumers on the
claim of SUPER Company on SUPER water.
2. Compare science and pseudoscience.
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Snapshots of Lesson 9
and Student Products
Students were
required to do
role play for
the Activity 2
(SUPER
Water)
• Group Presentationby a Salesman of the
SUPER Company
Student Presentation
• Group Presentationviews of Customers
on SUPER Water
• Group Presentationviews of a
representative of the
Consumer Council on
SUPER Water
• Group Presentationviews of Scientists on
SUPER Water
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Programme Evaluation
This programme was evaluated through classroom observation, student questionnaires
and face-to-face interviews. It was observed that the student participants were
actively involved in the classroom activities and they were motivated to learn. The
teachers could act as good facilitators to help students accomplish the different tasks
aimed to enhance students’ thinking skills. The learning environment was warm and
all the students were encouraged to express their views. The students enjoyed the
lessons very much.
The student questionnaires reviewed that the students were interested in this
programme and they believed that they could apply the knowledge learned to solve
their daily life problems. Feedback from the interviews was very positive and
encouraging. The students said that their critical thinking skills were enhanced and
the teachers appreciated very much that their students could learn critical thinking
skills through this programme. Finally, Dr. Chan Ho-mun, the programme consultant
mentioned that the programme design was very good because the topic content could
enhance higher order thinking skills and interdisciplinary learning, which in turn
would benefit students’ learning in the university. To conclude, this programme can
benefit the learning needs of the scientifically gifted because it provides advanced
learning content, focuses on the learning process and students’ product and puts
emphasis on the learning environment.
“Enhancing Thinking Skills in Science Context”
Pilot school: St Paul’s Co-educational College (2006-2007)
Student Questionnaire
Date：_____________
The purpose of this questionnaire is to collect your opinions and feedback to improve
the course content and the teaching methodology so that the learning needs of the
highly able students can be catered.
Put a tick in an appropriate box (i.e.) to indicate the degree of your agreement with
each of the following statements. Your answers are completely anonymous.
Strongly
disagree
Disagree
Agree
Strongly
agree
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1. I like this course.
2. This course was more interesting compared
with the traditional lesson.
3. We were free to choose the ways (e.g. by
text, drawing or other methods) we like to
finish assignments.
4. We had enough time to participate in
discussions during the course.
5. I learned the critical thinking skills from this
course.
6. My teacher encouraged me to express my
own ideas
7. We were required to solve the problem on
our own.
8. My critical thinking skill is improved upon
completion of this course.
9. I actively participated in this course.
10. On the whole, I was satisfied with the
course contents and activities in this course.
State the reasons why you like/ dislike this course.
What are your suggestions about this course?
Thank you
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“Enhancing Thinking Skills in Science Context”
Pilot school: St Paul’s Co-educational College (2006-2007)
Extract from Students’ Questionnaires conducted
on 27/ 6 / 07
State the reasons why you like/ dislike this course.
1. Useful.
2. This course is interesting compared with the normal class and I find it useful.
3. I can learn more knowledge.
4. Interesting. We can cooperate with different classmates and share our opinions
during discussion.
5. Novel questions. We can understand science more.
6. Relaxed.
7. Very interesting and interactive teaching in the classroom. We are free to
express our own opinions.
8. Because it is interesting.
9. I like it because I can learn science knowledge which cannot be learnt from
normal lessons.
10. I like it because it is interactive and fun. Very different from classes at school.
11. Interactive, interesting.
12. It is useful for science lessons.
13. I learn much from this course. My classmates are highly capable.
14. The course is interactive. I have a chance to discuss with others.
15. I can apply the knowledge to solve the daily problems.
16. The course is fruitful.
17. The activities are creative and interesting.
What are your suggestions about this course?
1. The lesson is too short so that some concepts cannot be fully explained.
2. If the lesson is longer, students can explain some other science questions to their
classmates.
3. The teaching approach of this course can be applied to the normal lessons.
4. Try to arrange this course in another time (but not after school). The only reason
that I don’t like the course is that I’m under the impression that it occupied my
personal time.
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Links of the Interview Videos
Behavioral Checklist of Students with High
Potential in Sciences
Name of Student:_________________________
Class:_______
Interview with Dr. Chan Ho Mun
http://resources.edb.gov.hk/gifted/tr/thinking_skills/
(Programme evaluation)
Interview with Students
http://resources.edb.gov.hk/gifted/tr/thinking_skills/
(Programme evaluation)
Item Behavioral Checklist
Never Sometimes Frequently Almost
Always
1
Show intense interest in science even
during the pre-school years and have
science hobbies (e.g. enjoy reading science
books, fiction, magazines, TV programmes;
active participation in the science club
and science competitions; pay frequent
visits to science museums; enjoy collecting
plant & animal specimens like a collector,
taking walks in nature and carry out special
science projects of their own at home)
2
Very knowledgeable in science information
besides textbook knowledge (e.g. science
tricks and science in everyday life)
3
Want to know how things work / why
things happen and find satisfaction in
thinking about and discussing scientific
affairs
4
Have a critical mind – would use
combinations of evidence and science
theories and principles to question other
people’s conclusions (including their
teacher’s)
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Age:____
Please give a “tick” against those options that best describe the characteristics of the
student.
Interview with Teachers
http://resources.edb.gov.hk/gifted/tr/thinking_skills/
(Programme evaluation)
Sex:_______
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Item Behavioral Checklist
Never Sometimes Frequently Almost
Always
5
Understand abstract science concepts at an
earlier age and can make good connections
between facts and concepts learned
6
Be able to use more extensive science
vocabulary than their peers
7
Willing to pass up entertainment such as
games and TV programmes in favour of
scientific pursuits
8
Prefer science related careers
9
Be self-motivated in learning science
and like to challenge self to try different
strategies to solve science problems and
persist until the problem is solved (willing to
spend long periods working alone)
10
11
12
Creative in science, daydreamers, like
to solve mental puzzles, and are able to
brainstorm many methods to solve a problem
and be able to make priorities for the
methods
Good at carrying out scientific investigation
- be able to create a new or clearer
definition of the problem, devise new and
more efficient or effective methods to
solve a science problem, able to formulate
hypotheses and conduct experiments
carefully.
With good laboratory skills and be able to
improvise for experiments.
Item
Behavioral Checklist
Never Sometimes
13
Good at numerical analysis,
measurement and data analysis - be
able to apply concepts of reliability and
validity in analysing the experimental
result
14
Be able to evaluate own experimental
design, suggest modifications to
experimental design and make
appropriate conclusion
15
Won school / inter-school / international
awards in science competitions and
demonstrate high quality work (such
as creativity and higher order thinking
skills) in science projects/assignments at
school
16
Usually have better-than-average ability
in Mathematics; many are also good at
mathematics and chess
Frequently Almost
Always
Remarks:
(1) School science teachers may fill out the checklist for students and compare the
number of items with ticks in the Frequently and/or Almost Always columns. Then,
those students who have more ticks in the Almost Always column should be strongly
recommended for the school-based gifted programmes.
(2) Teachers are advised to use multiple methods and channels (such as classroom
observation, parent/peer group/self recommendation, students’ products and
assignments, awards in local and/or international science competitions, etc.) to
select students with higher potential in science to school-based programmes for the
scientifically gifted students. A single test/identification tool is not reliable in the
identification of a scientifically gifted student.
(3) Teachers should not neglect those underachievers with high potential in science.
Many studies show that a challenging curriculum may reverse the underachievement
of the gifted underachievers.
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References:
References:
McGinnis, J.R. & Stefanich, G.P. (2007). Special Needs and Talents in Science
Learning. In S. K. Abell & N. G. Lederman (eds.) Handbook of Research on Science
Education. Mahwah, NJ: Lawrence Erlbaum Associates, Inc., Publishers.
Website of Qualifications and Curriculum Authority, UK (Identifying gifted pupils:
Science) (retrieved from http://www.qca.org.uk/qca_2184.aspx on 3 October 2007)
Feldhusen, J.F., Hoover, S.M.H. & Sayler, M.F. (1991). Identification and Educating
Gifted Students in Secondary Level. Australia: Hawker Brownlow Education.
Fliegler, L.A. (1961). Curriculum Planning for the gifted. Englewood Cliffs, NJ:
Prentice-Hall.
Angela Melamed (2005) Resources for Science for Public Understanding (T9.6/
Genetic Engineering/Chapter 7/page 1), http://www.scpub.org
Benny H. W. Yung (2006) Learning from TIMSS: Implications for Teaching and
Learning Science at the Junior Secondary Level. Hong Kong: Education Bureau.
Gregory Bassham, William Irwin, Henry Nardone & James M. Wallace (2008)
Critical Thinking: A Student’s Introduction (3rd ed.) New York: McGraw-Hill
Companies, Inc.
Peter Castro & Michael E. Huber (2005) Marine Biology (5th ed.). New York:
McGraw-Hill Companies, Inc.
Richard Gott & Sandra Duggan (2007) Understanding and Using Scientific Evidence.
London: SAGE Publications Ltd.
Stephen S. Carey (1998) A Beginner’s Guide To Scientific Method(2nd ed.).
California: Wadsworth Publishing Company.
方子華、陳浩文、盧傑雄、陳晧崴、楊國榮、余錦波 (2005) 《批判思考》
，新加坡：McGraw-Hill Education (Asia)。
王溢然、張耀久 (2001) 《類比》，台灣：凡異出版社。
香港消費者委員會：《選擇》(第357期(「神奇」水機健康聲稱備受質疑))
，香港：消費者委員會，2006年7月 。(https://choice.yp.com.hk/consumer_
council/ch/html/main.aspx)
Recommended Book List:
Anne Thomson (2006) Critical Reasoning: A Practical Introduction. London:
Routledge.
Linda Elder & Richard Paul (2007) The Thinker’s Guide to Analytic Thinking.
California: The Foundation for Critical Thinking.
Richard Paul & Linda Elder (2006) A Miniature Guide for Students and Faculty to
Scientific Thinking. California: The Foundation for Critical Thinking.
岳燕寧 (2001) 《歸納與演繹》，台灣：凡異出版社。
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